question

[sereners]

I have a question concerning the k-1 fiance visa….i understand and have all the paperwork for the whole process to be done ligally and in the near future but my question is i hopefully will be eventually moving to the us with my boyfriend that ive been dating for almost 2 years and i have a daughter that will be coming over with me but i have a son that my ex has full custody of and that i have every Friday until Sunday….ive been told that when I get accepted to enter the usa I canot leave for 3 months…my question is is there any way there are exceptions for this or any options to be able to continue to go and get him and bring him home??

Thank you for you patience in responding to this