I have 8 AM tickets for the Vatican Museum on a mid February Thursday, and plan to check out St Peters and climb the dome that afternoon. I will exit the museum to eat lunch in Prati then walk back to St Peters, and want to allow plenty of time for food + a stroll.
In the winter the dome is open until 5 and the Basilica is open until 7:15. Should be good if I book 4pm tickets for the Basilica + Dome? How bad is the line for the tickets on a February weekday afternoon? If the line isn't too bad, I'd prefer the flexibility of showing up whenever I finish walking about, but I will surely prebook if the wait is expected to be bad.