It is too long if you cannot tighten it once the sail is correctly fitted at the mast. The idea of the loose foot is that you can tighten it when sailing upwind or in strong conditions, but slacken it a bit for good sail shape and maximum power downwind and in light winds. On my boat I do not have enough deck organisers and jammers to lead the outhaul back to the cockpit, but if you can do that it enables you to tweak it easily.
With a loose footed main it helps if you have a decent outhaul car running in the boom track. On your old sail did you have a car, or was the clew shackled direcly to the outhaul from the sheave in the boom end? If the latter I hope your sailmaker allowed for the addition of a car and made the foot of the new sail a few inches shorter than the old one. On my boat when the outhaul is tight there is still an inch or two of outhaul car movement available.