J1 visa conversion to a B1/B2 visa?

Hi. I'm a doctor who's finished my Pediatric residency on a J1 visa. I'm currently in between jobs and will be applying for my J1 waiver in a few weeks. I, with my 3 year old son (who has an American pport) are currently out of the USA but would like to come to the USA to be with my husband (whose got a green card and is a doctor too) until the waiver comes through. Can I apply for a B1/B2 visa and stay with him in America until the waiver is approved? Once approved, would I need to exit the USA and re-enter? I plan to obtain my visit visa from London. They were the ones that stamped my initial J1 visas. Thanks for all your help!! :)