Actually, Cyberhawk, this may surprise you: there are at least 2 different dates for the commissioning of the Constitution-class starships........the first is in the 2240's, and this is according to the 1970's book "The Making of Star Trek". The other date is round about 2214-2220, and this is according to the Starfleet Technical Manual by Franz Joseph, also published in the 1970's, but you have to be able to read the stardates he uses. Our game, SFC, if you take a close look, assumes the 2220's date because that's the date that SFB uses.
Actually, the Starfleet Technical Manual says that there were "batches" of Heavy Cruisers made at certain dates in the 23rd century, the batches each having class names. The first batch was the "Constitution", the second "BonHomme Richard", the third "Achernar". The BonHommes were contracted in the 2230's and built and launched in the 2240's, according to the dates in the Manual. At some point, the original 1701 had to have recieved an upgrade to the BonHomme specs, and this was probably in the 2240's.