draftees will become available after the allstar game, i would only invest in 2 per week and save them till the end of the season and only do the scouting combine this season, sorting the players by ages then by position selection, if you want bigs put the bigs up to or guards small guys up top etc etc. save the rest of your points.
it wont take as long as you think to build your arena up if you just keep at it, if you stray away from building and waste money on useless players then it will take a long time.
after the this season and next season you should be at the mark, and if you save all but 10 draft points from this season plus draft points from next season you should have around 40-50 points, then you can do some serious scouting and find yourself a trainee or two to either pair with the guys you trained over this and next season or to replace them. then you start adding players, and your golden