Can I change my start date to February
Hi. That depends on a number of factors such as when you applied, whether or not you are under full retirement age (FRA), whether you're changing your month of election (MOE) to an earlier or later month, and whether or not anyone else is eligible for benefits on your account. Since there's not enough information in your question for me to be able to give you a proper answer, I would suggest that you call Social Security to discuss your options with a claims representative.
I can tell you that you definitely would not be permitted to change your MOE to a month that isn't permitted under Social Security's regulations. For example, if you're under FRA and applying for retirement benefits you couldn't change your MOE to a month that precedes the month of filing of your original application.
If you've only recently applied and if Social Security hasn't yet processed your claim, then you could probably change your MOE by contacting Social Security and asking to amend your application. If your claim has already been processed, though, then you'd need to submit a signed and written request to change the start month of your benefits. You could use a form SSA-795 (https://www.ssa.gov/forms/ssa-795.pdf) for that purpose.
Best, Jerry