How to guage when my products will be avaibale to purchase

Hi all,

When inputting my listings, the only option I have for any type of release date is "offer release date." I will be doing FBA, but how would I know what to put for the "offer release date," assuming the "offer release date" means the date it goes live on amazon. I want to time out my "launch" for advertising purposes, but I've read different things that contradict when the products actually go live on amazon and become available for purchase. I understand once they are received and stocked in the warehouse they will become available to purchase, unless I have an offer release date beyond that?

Any guidance is greatly appreciated.