I like to wait until after leaf out(later spring here in VA). Maple's have a heavy sap flow when pruned in early spring. Although this does not "hurt" the tree it does make people nervous. They think the tree will "bleed" to death.
To add to Jays "leaf out" statement; wait a few weeks after the leaves are full sized. This will allow the tree to replenish the reserves expended in pushing out the new growth.
Lopping off a number of low branches is not always the best thing for a tree either. Reducing their size may be better.
Please be carful on the amount you prune off. Remember you can always take a branch off next year if you have any doubt. I don't like taking any more than a quarter of the canopy if I really need to clean up a structurally poor tree.