Boss wants me to go full time

I started Aug 25th and my hours have been 11-5 because I originally wanted part time an the hours work out so I can run errands in the morning. (I like to do all my grocery shopping/appts first thing am to beat the traffic/crowds.)

Well, my VP (my direct boss) pulled me into her office the other day and praised me for my work. She said I am professional, diligent, and she’s so impressed with my work. The only thing that we need to work on is being more in sync.

She also asked how I like my hours, (again,) and it feels implied that she wants me to work the 9-5 schedule.

I believe if I do switch this can help with us being more “in sync” but if I do, then I’ll lose out on my morning errand time.

My current hourly pay is 18.50/hr. My question is; If I were to switch to full time, would I/could I/should I ask for a raise?

I have not been here for 90 days, but the feedback has been very positive. (She even ask me to mentor a younger EA from a different side of the company, (think one big umbrella business, with a couple smaller side businesses; I am under the Big umbrella and this EA is in one of the smaller sides. This EA is young without any office experience, so she just needed some feedback on how to be more effective for her manager.)

If Yes, I can ask for a raise, how much would be appropriate? I’m in the Midwest, in a low cost of living state. Personally, I’d want to be $20/hr even, but that sounds like a hella big ask for being under 90 days.

If no, when would I ask, and how much should I ask for, if anything?

Should I just deal with it and switch to full time? Even if that means I’d lose out on my personal time?

Any advice is appreciated.