On Sunday the 27th I am having my first shower!

It's at my FMIL's house and being thrown by family friends and FSIL. So I got gifts for family friends, FMIL- since she has done so much and it's at her house, and FSIL.
When do I give them the gifts?
Do I write a thank you note pre and post shower?
Do I just say something like "here is a gift in appreciation for all you have done"? I'm never sure if people know ettiquite (especially since I learned it on TK).
TIA!
P.S. I got my cathedral veil yesterday from Obridal! i LOVE it:)