on whether you can go early..that depends on individual offices i suppose...my wife got her notice later than I did.When I had my fingerprinting done,i asked them whether she has to wait till the scheduled date...the reply I got was as long as she has the fingerprinting notice,she can come in early...we did that and had no problems.
This was at Albany,we went on a Wednesday ...which is the day listed on our notice if you can't make the scheduled date
Long story short..give it a shot,you have nothing much to lose