Meghan will have to give up a lot financially though, and that will be a real dilemma, I feel. Will she give up Suits (if she hasn't signed a contract for a seventh season of the show) and move to London in the next few months, trusting to Providence to Harry and to their future marriage? What if it doesn't work out? That would be a considerable sacrifice made for naught.
On the other hand, if Meghan waits until the ring is on the finger Royal engagements are traditionally short. Would there be enough time to learn about the BRF protocol, Britain, British way of life etc etc? The financial sacrifices under those circumstances too would be quite considerable, but at least there will be a marriage at the end of it.