Got new plan today, speeds not reaching expectations.

Hi, so I got Cox Ultimate today and in my area the Max is 150/20 or 188/25 with powerboost. I am getting 90/10, this was also the case when only one device was on the modem during setup. Is it normal to have these speeds on average with it only peaking to 150 sometimes? Or is this on the low side, if it is, should I do something about it, thank you.