I work full time as well (9-10hrs work + 2hrs driving), I have two small kids and a full zoo of pets at home 😉 I did F4, F9 and P1 in Dec and passed them all, so will now go ahead with P2 and P3. Two papers at time is pretty doable, and I can admit I’d be way too impatient to do only one paper..
So if I were you, I would do both. But of course it is still up to you. If you know you won’t have time/motivation/money/whatever to do both, then of course leave one till Christmas 🙂