I would say this depends right. If he's/she's got extra time to burn, why not take anatomy rather than basketweaving 101. I wish I had taken it. Does this mean you can't do well if you haven't done it before? No. But we do work harder than those that are more familiar with it.
I think it would have been a lot less stress if I had. So OP, it's up to you, but if I had to redo some things, I would have taken anatomy, especially since my undergrad had a really good prof whose lectures (some of them are on youtube) - Professor Diamond from UCB if you're curious in looking it up.
Just like med school biochem has a completely different focus than undergrad biochem - but having taken the undergrad biochem gives you a sense of familiarity. And both will overlap (hello Krebs cycle for the 100th time) at some points.
You might want to check out the Step 1/USMLE advice thread for what different people did. One size fits all won't work here. Depends on your school, depends on how well you study, depends on what the lectures cater to (PhD minutiae that the lecturer cares about random x protein that you'll never see again vs having Professor Goljan for your lecturer). I'm still in MS1 but I have flipped through FA, most of the stuff we learned so far isn't in there, not at all. And things that I thought I was good at, like micro, dear god there is a whole another level of detail in FA, not quite Fields Virology level but I can tell there's a lot of work to do. I might (thought doubt it) look at parts in FA to familiarize myself with the outline/what subjects to focus on and maybe go over what we've covered so far, but MS2 when you actually learn the stuff seems to be the time to do it.
Btw when you go the Step 1 advice threads - check the posts under Long Dong and Jalby, they are famous for their high scores and Step 1 advice. Two completely different methods but it worked for both of them.
Oh, and yes enjoy your summer before MS1. Truly. I went paintballing (hellooo headshots) and apple picking a couple days before I left, and I'm glad I did.