I am planning on going to Greece with in the next three months, I will only be in Italy until May 12. I want to go to Mykonos when things are opened up and the night life is active. When is the best time to go?
Micki - May is an awesome month for Mykonos - The other choice is towards the end of the season in either September or October. Paradise Beach Hums and usually starts about 11:00 P.M. and goes until morning - BE READY!!!!!!!!!!!!!!
For me mid-May through June is the best time but September is also good because the crowds have already started to thin out. October is a bit too windy and chilly for my idea of the best Greek island weather, especially at night.
Since you have a three month window and want Mykonos, then the answer is as late in the three months as possible. The islands will start winding up just after Easter, though even the first week of May will probably be a little tame. The water will still have a chill as well, but better than Italy. The best nightlife is in August I suppose, but the volume of people drive me into September when some of the crowd has left, but the weather and water are wonderful. Even then, some venues can be quite dull.