Doubt on custom workflow

Hello All,

I am creating custom workflow in Project Server 2013 using Visual Studio 2012.

My workflow is triggered in the event 'OnProjectSubmit', this is the event when one clicks on 'Submit' button so does this mean that however the workflow logic is, by clicking on 'Submit' button by the user it will pass from one stage to another. Is this right?

So my problem is, I want to add a logic which is almost like the below

If ('customfield' == 'Yes')

Leave Stage;

else

remain on the same stage

Can I achieve above condition in the 'OnProject Submit' event, if yes then how?

Thanks in advance