I went to the draft for the last five years in a row and this will be the first time since that I will not be attending. You would need to get to MSG before 7:30 a.m. at the latest to guarantee admittance. Once you get there, look for the ushers that hand out wrist bracelets. Once you get one, you are guarantee enterance into the draft. Once you have the bracelet on, you would then have to wait until about 10:30 in line before the line starts to move. Sometime around 11, they will let you enter the theatre and you can find your seat anywhere you like. If, per say, that you find a seat in the back and wish to move up, around when the fifteenth overall pick of the draft is up, you will notice that some people have left and therefore seats toward the front are available. The league also introduces a number of players that were invited to the crowd, have a multiple choice game with Giants and Jets fans, and have a mock draft contest in which you pick who gets drafted by who in the first round.
My suggestion if you live close to MSG is to arrive there around 6 a.m. Then you have a better chance to get a better seat at the draft and you will be impressed as to how many fans show up and who is represnting all the different teams in the league. If you don't mind standing in line as if you were waiting in line for concert tickets, it's worth it.