diff --git a/.rubocop.yml b/.rubocop.yml
index f9e7add9f9..702224887a 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -118,7 +118,7 @@ Metrics/MethodLength:
   Max: 29 # TODO: Lower to 15
 
 Metrics/ModuleLength:
-  Max: 217 # TODO: Lower to 100
+  Max: 227 # TODO: Lower to 100
 
 Metrics/ParameterLists:
   Max: 8 # TODO: Lower to 4
diff --git a/lib/rails_admin.rb b/lib/rails_admin.rb
index 7f70d4d507..fee9e267d6 100644
--- a/lib/rails_admin.rb
+++ b/lib/rails_admin.rb
@@ -29,7 +29,9 @@ def self.config(entity = nil, &block)
     if entity
       RailsAdmin::Config.model(entity, &block)
     elsif block_given?
-      RailsAdmin::Config.apply(&block)
+      # Immediately evaluate non-model (initializer) config. It's needed to
+      # properly configure routes when there are custom actions.
+      yield RailsAdmin::Config
     else
       RailsAdmin::Config
     end
diff --git a/lib/rails_admin/adapters/mongoid/extension.rb b/lib/rails_admin/adapters/mongoid/extension.rb
index e669c693a5..3803525a24 100644
--- a/lib/rails_admin/adapters/mongoid/extension.rb
+++ b/lib/rails_admin/adapters/mongoid/extension.rb
@@ -11,9 +11,7 @@ module Extension
           self.nested_attributes_options = {}
           class << self
             def rails_admin(&block)
-              RailsAdmin.config do |config|
-                config.model(self, &block)
-              end
+              RailsAdmin.config(self, &block)
             end
 
             alias_method :accepts_nested_attributes_for_without_rails_admin, :accepts_nested_attributes_for
diff --git a/lib/rails_admin/config.rb b/lib/rails_admin/config.rb
index 531b6701b4..48c0426403 100644
--- a/lib/rails_admin/config.rb
+++ b/lib/rails_admin/config.rb
@@ -24,6 +24,7 @@ module Config
 
     # Variables to track initialization process
     @initialized = false
+    @initializing = false
     @deferred_blocks = []
 
     class << self
@@ -87,6 +88,9 @@ class << self
 
       # Finish initialization by executing deferred configuration blocks
       def initialize!
+        return if @initializing
+
+        @initializing = true
         @deferred_blocks.each { |block| block.call(self) }
         @deferred_blocks.clear
         @initialized = true
@@ -226,6 +230,7 @@ def default_search_operator=(operator)
 
       # pool of all found model names from the whole application
       def models_pool
+        initialize!
         (viable_models - excluded_models.collect(&:to_s)).uniq.sort
       end
 
@@ -238,7 +243,7 @@ def models_pool
       #
       # If a block is given it is evaluated in the context of configuration instance.
       #
-      # Returns given model's configuration
+      # Otherwise returns given model's configuration.
       #
       # @see RailsAdmin::Config.registry
       def model(entity, &block)
@@ -254,9 +259,24 @@ def model(entity, &block)
             entity.class.name.to_sym
           end
 
-        @registry[key] ||= RailsAdmin::Config::Model.new(entity)
-        @registry[key].instance_eval(&block) if block && @registry[key].abstract_model
-        @registry[key]
+        # When a block is provided defer evaluation until initialize so that:
+        #
+        # 1) performing configuration in the initializer does not attempt to
+        #    autoload model classes, and
+        # 2) model config blocks run after models are fully loaded and
+        #    associations are defined.
+        #
+        # Do not defer when called without a block as the model must be returned.
+        if block
+          RailsAdmin::Config.apply do
+            m = model(entity)
+            m.instance_eval(&block) if @registry[key].abstract_model
+          end
+          nil
+        else
+          initialize!
+          @registry[key] ||= RailsAdmin::Config::Model.new(entity)
+        end
       end
 
       def asset_source
@@ -318,6 +338,8 @@ def models
       #
       # @see RailsAdmin::Config.registry
       def reset
+        @initialized = @initializing = false
+        @deferred_blocks.clear
         @compact_show_view = true
         @browser_validations = true
         @authenticate = nil
@@ -356,10 +378,8 @@ def reset_model(model)
 
       # Perform reset, then load RailsAdmin initializer again
       def reload!
-        @initialized = false
         reset
         load RailsAdmin::Engine.config.initializer_path
-        initialize!
       end
 
       # Get all models that are configured as visible sorted by their weight and label.
diff --git a/lib/rails_admin/engine.rb b/lib/rails_admin/engine.rb
index 788071eff6..b462fb557d 100644
--- a/lib/rails_admin/engine.rb
+++ b/lib/rails_admin/engine.rb
@@ -68,11 +68,6 @@ class Engine < Rails::Engine
         ERROR
       end
 
-      RailsAdmin::Config.initialize!
-
-      # Force route reload, since it doesn't reflect RailsAdmin action configuration yet
-      app.reload_routes!
-
       RailsAdmin::Version.warn_with_js_version
     end
   end
diff --git a/spec/rails_admin/config_spec.rb b/spec/rails_admin/config_spec.rb
index 521515960c..bf1f27dd04 100644
--- a/spec/rails_admin/config_spec.rb
+++ b/spec/rails_admin/config_spec.rb
@@ -327,6 +327,24 @@ class TestController < ActionController::Base; end
       end
     end
 
+    context 'when a block is not provided' do
+      let(:model) { described_class.model(Team) }
+      it 'returns the model config' do
+        expect(model).to be_a(RailsAdmin::Config::Model)
+      end
+    end
+
+    context 'when a block is provided' do
+      let(:model) do
+        described_class.model(Team) do
+          field :fans
+        end
+      end
+      it 'does not return the model config' do
+        expect(model).to be_nil
+      end
+    end
+
     context 'when model expanded' do
       before do
         described_class.model(Team) do
@@ -387,6 +405,7 @@ class TestController < ActionController::Base; end
       end
     end
     before { RailsAdmin::Config.instance_variable_set(:@initialized, false) }
+    before { RailsAdmin::Config.instance_variable_set(:@initializing, false) }
     after do
       RailsAdmin::Config.instance_variable_set(:@initialized, true)
       RailsAdmin::Config.instance_variable_set(:@deferred_blocks, [])
@@ -445,6 +464,11 @@ class TestController < ActionController::Base; end
       expect(RailsAdmin::Config.model(Team).fields.find { |f| f.name == :color }.type).to eq :color
     end
 
+    it 'does not immediately apply model configuration' do
+      expect(RailsAdmin::Config).not_to receive(:initialize!)
+      RailsAdmin::Config.reload!
+    end
+
     it "applies the initializer's configuration first, then models' configurations" do
       # simulate the situation that Team model is loaded in the middle of processing RailsAdmin initializer
       allow_any_instance_of(RailsAdmin::Config::Model).to receive(:include_all_fields).and_wrap_original do |method|