If I could answer your question accurately 100% of the time I would be very rich, since the cruise lines would pay me to adjust their prices for maximum yield.
Some cruises sell very fast. I know of one that I was interested in back in 2004 that sold out six months before the cruise. I didn't get to go on that one. I know of another that also sold out six months before the cruise. I'm on that one.
Others don't sell out until two weeks before the cruise.
That said, you are looking at a cruise that departs during school time and during hurricane season. Thus, I would not expect it to sell out quickly.
That said, why not put a deposit down now. You can always cancel and get a full refund up to about 90 days prior to the cruise date. Also, if you book now and prices go down, you can rebook at the new lower price. If prices go up, you get to keep the old lower price. However, if you don't book now, and prices go up, you don't get to ask for the old lower price.
My next cruise the prices have doubled. I got in early at the much lower price. My next cruise after that went down in price for a short time. I was able to rebook at the new lower price. The price then went back up. I get to keep the old lower price that I rebooked at.
