The FM comat first is not ideal but everyone else taking it will be in the same shoes. Try to learn a bit of derm, a bit of basic msk, a bit of basic peds, and don't focus too much on OB/GYN IMO. Coming off step 1 will actually help you though.
Know all USPSTF guidelines cold! Amboss has an FM shelf qbank. Don't use any combank questions for anything ever during med school (truelearn can be used for residency/specialty board exams). Some people use comquest during third and it is considered good for most Comats. That said, I was strictly of the opinion that any time doing comquest is time taking away from doing UWorld to prepare you for Step 2. I didn't do any questions besides UW for third year.
Use divine intervention podcasts specifically for FM. Just trust me.
How does your school select honors for comat grades?
Edit: I want to add that you should approach COMATs like you did with comlex. The timing is more important than anything so address this if you are a slower test taker. Read the last line first then the question. Make your brain just subconsciously ignore OMM unless it is a strictly OMM question. If you have no idea what the **** is going on then choose an answer, flag, and come back. The questions aren't hard. They pretty much all just require knowing some random fact. You can use previous questions to help answer questions later in the exam. Don't be caught off guard by the same question being asked twice or having like 7 questions on essentially the same thing. Just roll with it and enjoy the rest of your day. You got this!