pumping for stash with overactive letdown, bad idea?

miniray

I have an overactive letdown im starting to get it under control. Laid back nursing and side lying nursing are helping and Im feeding one side per feeding. Anyway, its my 30th birthday next weekend and DH wants to take me out to dinner. LO cluster feeds in the evening so I want to leave at least 2 bottles with grandma in case he gets hungry. I want to pump after first morning feed to get some milk frozen. Is this a bad idea and will make my over supply worse?