Months. Once there is any kind of even remotely capitalism-accepting government in place the construction contracts will roll in. The only reason it isn't there ~now~ is just because of Fidel's habit of nationalizing any foreign investment capital, like... oh, a new resort building. The day that it looks like investments there will remain the property of the owner... the contruction cranes will appear the following day. Hilton, Marriot, Bally's... there won't be enough construction equipment in Cuba to keep up with them.
Months? Oh, I'd love to see that.
Now, all we have to do is wait until Fidel drops dead during one of his 6-hour speeches.
Can you imagine the glee of the crowd when they realize it's finally happened?