Cant tell you when,I just planted Ice Cream banana's out. But I can tell you..they do best in your hottest locations. There's a reason the largest and tallest banana plants seem to be along driveways in the Bay Area- between the house wall and concrete or asphalt surface. That's another half zones worth of heat.

I have a goldfinger in Scottsdale, now abut 6 - 7 feet. grew 3 feet this summer. As long as the temp remains above 57 degrees or so they will continue growing, that is why I planted them next to the house. According to the literature If I can keep some growth continuing over the winter, they will fruit by next late summer, About 15 months.