Totally depends on the school. Some schools do rolling admissions, some do not. Whether or not applying early is beneficial depends on what schools you are applying for.
Often it is the case that state schools have hard deadlines and do not use rolling admissions, while many of the private schools do use rolling admissions and try to fill their classes earlier (before offers from more attractive state schools come out, no doubt). Don't count on this always being the case, but it was the case for a bunch of the schools I looked at.
Advise your friend to research each school carefully and call the admissions departments for needed clarification. DPT programs seem to be more heterogeneous than med programs as far as what they require and how their admissions process works. Everything to do with admissions timelines, processes and requirements varies widely from school to school, so careful research really is needed. A lot of people waste a lot of money every year applying to schools where they either don't meet the admissions requirements, or don't stand a chance of acceptance.
PTCAS does look and function very similarly to AMCAS though, as far as I have observed. Basically the same software with different colors and fields to fill in.
And August is a bit late for the GRE at some of the more competitive rolling admissions schools, but not too late for programs that have hard deadlines in Nov./Dec.
Hope this helps 🙂