if you already have B2, no need to go K1. K1 is for those who have no
chance of getting B2.
marry after 90 days in US, if your purpose is to live in USA, wait 3-6
months before you deal with USCIS doesn't cost you much. Usually it's
parent category who want to file it faster, because the elderly parents want
to leave USA as soon as they got AP and can barely meet 1/2 living time in
US after getting GC, but you want to stay in US long term, right?