Do order of lines matter when applying inference rules?

Question

The wikipedia shows the form of Modus ponens as

1. If P, then Q.
2. P.
3. Therefore, Q.

With 1 being the implication and 2 being the antecedent of that implication.

When applying the rule, I would cite the lines in that order

1. p -> Q       Hypothesis
2. P            Hypothesis
3. Q        1,2 Modus Ponens

Would it be impure form for me to instead write

1. p -> Q       Hypothesis
2. P            Hypothesis
3. Q        2,1 Modus Ponens

With the order of the arguments to be plugged into the Modus Ponens function reversed?

Or should you always cite lines in the order corresponding to the form definition, regardless of the order they actually appear in the proof?

1. P            Hypothesis
2. p -> Q       Hypothesis
3. Q        2,1 Modus Ponens