veteran rewards question

I am at rank 4 veteran rewards atm. I have an automatic renewal option set up but I want to be rank 5 when the new veteran rewards gets released.

Can I buy more days early or do I have to wait until my time is up? Also I did not see the option to buy more than 180 days on mog station.

180 days is the max you can subscribe for as far as I know. I cancelled my 90 day sub and set it up for a 180 day sub so that i can get the behemoth mount when my next payment is due in a few days.