Is this an okay improvement rate?

MadSpaceCow
Tue, 16 Jul 2013 18:40:14 +0000

I just started studying for the SAT this Summer and I have started with Math. My scores improved a lot at first, but now that has slowed down. Is this normal, or should I be worried? Here are my test scores(all from the Blue book):

600
620-680
570-650
670-730
670-730
690-770
660-720

I really want to get a 2300+ come SAT time, and math has always been my worst so I really want it to improve.