Changing I-129 petition after booking H1B-transfer visa stamping appointment

Hi, I’m about to go through an employer change with H1B transfer soon, and want to set up a visa appointment in India (new delhi, drop off) as early as possible.
Would it be ok to go through the appointment process with my old petition, get whatever appointment is available for early next year and then update my DS-160 to be the new employer’s petition that I expect to have in the next 4 weeks.
I understand that the DS-160 can be updated as late as 2 days before the interview, but the interview scheduling system also asks for petition details at some point and I am concerned that changing that for an existing appointment might invalidate the fees/appointment, or cause other complications in processing.
Has anyone done this sort of thing before?