There are dual opinions on that. If your insurance premium is of the greatest importance to your decision then by all means wait as no one can truthfully predict how much the new premiums might be.
However, keep in mind that if all insurance premiums were to soar out of reach immediately after the maps are released , Ocean City as well as many shore towns would become ghost towns. The real estate markets would come to a stand still. That is not the intent. The government both state and local are looking to protect the economies of the towns, yet keep the FEMA insurance program solvent. Most likely there will be designated time periods where insurance premiums will gradually increase. Homeowners that can take advantage of the various grants being offered by the federal governments will be given the opportunity to make their consistently flooding homes less likely to be destroyed by floods in the future. Raising a home is a must for those that suffer severe losses. Obviously, the less likely a home is to destruction the lower their flood insurance premiums will be. If a home has sustained little or no damage the impact should not be as severe as a home that clearly needs to be raised because the damage was more than 50% of it's fair market value. Either way my opinion is a home in Ocean City is a great value. Don't forget that if you wait the mortgage rates are going to raise !!