As long as you have an ESTA (assuming British passport) you are fine (UK is exempt of the Six Months Rule). I'd recommend using and downloading MPC for immigration queues if your airport of arrival has it and provided you have already been to the U.S. once before, it's free (and no interview needed) compared to Global Entry and it's even shorter queues. Used it in MIA two months ago and I queued for 10 minutes in the U.S. resident section while the general visitors queue was over 2 hrs wait.