Here is how I look at the choices you have
1. Book your cruise when you want, get the cabin category you want, the cabin location you want and then enjoy the fact that your booking is settled.
Or
2. Wait, and hope that a restricted rate will come available for the date you want, all the time stressing and looking, and waiting, and hoping that it will happen. And even if it does, you wont know exactly what you got - what deck will I be on, what location will I get. What if you don't like forward or aft, or a high deck or a lower deck. What if that's what you get by booking a lower restricted rate?
I am speaking for myself, but I would rather pay a bit higher price to get what I want, where I want. I also love that I don't have to stress about something that may or may not happen. That is worth the extra $$$ to me.
Because I am a planner and love having everything settled ahead of time. Others, it may not be stressful to wait and hope. It just may depend on your preference. If saving some money by waiting doesn't stress you out and you don't care where your cabin is, then wait and book that restricted rate.