u/lexsan18

I am looking at expanding and was curious. If I purchase a complete lower, since the ATF considers this to be THE firearm, could I purchase a few complete lowers before the August deadline and be with in the law and add the uppers later? Hope that makes sense. There are a few pieces that are more than I'd like to spend, but can justify it if I can buy the lowers now, and have them grandfathered in?