honestly i love seeing older generation posting in the 40s and up, i have always felt like i started school late because i did my time in the army, but this motivates me, I am turning 35 in May, hopefully I will be starting law school at 35 or 36
my take is that practice tests as early as 1-10 are not going to be useful to you. you're unlikely to do all 87 PTs anyway, so just start with the 40s if you're worried about running out of material
I have found that the frequency of formal logic questions characteristic of the 20s is NOT found in the 70s! (Haven't done the 80s yet so can't speak to that, but I've done lots between 20s and 40s and now am in 70s).