Can I renew my controle technique a month early?
Yes, I think it can be renewed at any time after 6 months (in case of sale). The early month won’t be carried over though.
Basically, you can do it whenever you like but there’s no benefit in doing so as you don’t get any extra time on it.
Always grateful it is every 2 years here and the first when 4 years old.
First after 3 years and then every year in UK.
Feeling smug 
I was quite surprised my motorbike is 3 years and more than pleased that my old Saab is 5 years.
No problem with renewing CT early,you just lose the time left on the old one.