This is apparently not going to work with already loaded associations. Just testing around I got two different issues:

```ruby
# consider the models `Author` has many `Post`s

## 1st scenario - raises exception
>> carlos.posts.reload.first
  Post Load (0.1ms)  SELECT "posts".* FROM "posts"  WHERE "posts"."author_id" = ?  [["author_id", 1]]
=> #<Post id: 1, author_id: 1, title: "ZOMG", body: nil, created_at: "2014-01-21 11:44:22", updated_at: "2014-01-21 11:44:22">
>> carlos.posts.reload.second
  Post Load (0.1ms)  SELECT "posts".* FROM "posts"  WHERE "posts"."author_id" = ?  [["author_id", 1]]
NoMethodError: undefined method 'first' for nil:NilClass
  from....rails/rails/activerecord/lib/active_record/relation/finder_methods.rb:449:in 'find_nth'


## 2nd scenario - returns the same record
>> carlos.posts.first
=> #<Post id: 1, author_id: 1, title: "ZOMG", body: nil, created_at: "2014-01-21 11:44:22", updated_at: "2014-01-21 11:44:22">
>> carlos.posts.second
=> #<Post id: 1, author_id: 1, title: "ZOMG", body: nil, created_at: "2014-01-21 11:44:22", updated_at: "2014-01-21 11:44:22">
>> carlos.posts.third
=> #<Post id: 1, author_id: 1, title: "ZOMG", body: nil, created_at: "2014-01-21 11:44:22", updated_at: "2014-01-21 11:44:22">
```

@terracatta can you take a look please? It'd be good to provide some tests for already loaded associations with some of these methods. Thanks.