Verbal score is ALWAYS important, because you use it so often (you used your verbal knowledge to type at that post!)

But to answer your first question, you should re-take the GMAT during the perfect period where you feel ready without forgetting knowledge.

So, depending on how much you study (and how often)- you should estimate how much time you need (+/- a week of procrastination/important events) and schedule your next GMAT appointment.

I've made the mistake in the past of scheduling my GMAT 6 months out in advance, and ended up procrastinating (or studying VERY infrequently for the first few months, and doing a mad dash to the finish- and resulted in poor quality studying)