Its 40 +80 +50 = 170 fuel to get 1st p2.
And dont forget, that if you decide to build one p2 you kind of fucked for a long time, because the other tank from t4 is panther for another 170 fuel. Good luck getting this in competitive match as okw. (you could get puma if you went t3 instead of t2, but who goes t3 t4 as okw, not beign able to heal your expensive infantry)
OKW starts with 40 fuel, so your math is flawed at its base.
Now, think why you need early puma.
To counter US or sov light armor.
Exactly what P2 can do. By 10-11 min you'll have both P2 and puma if you convert fuel.
Its all about how do you manage your eco and unless you base your infantry on Obers, pios or fallshirms, healing isn't really needed that much early.