Since you are in dead calm, I would think it reasonable to do your turn when the wind fills in.
It may be reasonable, but might not be legal. RRS 42.2 "One-Turn and Two-Turns Penalities" states (emphasis mine):
After getting well clear...as soon after the incident as possible, a boat takes a ... penality by promptly making the required number of turns...
I once asked an international judge to clarify "promptly" for me, and he said to substitute the words "without delay".
Now, if the boat is truly becalmed such that it is not possible to get "well clear", then it's okay to wait. She must, however, take her penality as soon as possible when the wind allows.
Regards,
Eric
