When documenting your Salesforce Org you will find that it is easier to add documentation at the same time as you are creating or changing a new object, validation rule, field etc. when your understanding of the purpose for the change in your Org is still fresh.
Rather than wait for the automatic sync, you can perform a partial sync of your Salesforce Org Model, i.e. you can update just a part of your Org that you changed in order to fetch the latest configuration and start documenting fresh.
Right-click on an object, or any of the children nodes like fields or records, and select option Partial sync from Salesforce. You will see a message informing you that the partial sync has started.
You can also select the refresh icon in the right panel for the selected object or any of its children nodes (fields, validation rules, etc.)
You will be notified when the object and its data has been updated.
We are working on the ability to partially sync all custom objects which will allow you to bring all the new custom objects that you created.