Thank you for reaching out to us.
We appreciate that this can be a stressful situation.
This is a case in which we would recommend performing
preparations for mikveh early in the day. That way, at night, you can just rinse off in the mikveh, clean your teeth, run your fingers through your hair, and inspect yourself visually.
To keep preparations simple, it could be helpful to wear thin gloves for any work in the kitchen with dough. We'd also recommend holding off on a complex costume till Purim day and taking special care to avoid the glitter or make up that proliferates toward Purim until after immersion.
In terms of logistics, we suggest beginning by working out when there are megilla readings available throughout Purim night and when the mikveh is open. If none of the times work out, even with you and your husband taking turns for megilla, then you could try to get a friend or babysitter to help or to make special arrangements for a late-night immersion for after the kids are asleep and you've both heard megilla and eaten.
We hope that this can come together for you with advanced planning. If you cannot make this work, then the two of you can agree to postpone mikveh to Friday night.
Please don't hesitate to follow up with us. Purim Sameach!