How close to your renewal date do you allow yourself to be before you renew it?

On the one hand, I want to make the three years last as long as possible, if that makes sense, but on the other hand, I don't want to push my luck and get too close in case the course gets cancelled at the last minute and I can't find another one in time.

Mine is due for renewal at the end of June. I have found a course in April and another one in May. DH thinks I should do May, but I'm tempted to do the April one just in case. What would you do?