F.B.
Haven't done it myself. A close girlfriend just did though.
She put childcare in place two weeks before her start date and orchestrated her days as though she were going to work. Getting up early, dressing as if for the office, dropping kids off at daycare, keeping busy from 9-5 (brushing up skills, updating her wardrobe etc). She took a 45 minute lunch, by the clock, limited herself to 2 5 minute personal calls. Left as if she were leaving at closing time collected the kids, did homework, dinner, the evening routine etc.
She was getting her kids and herself acclimated to the new routine, and working out the bumps.
She practiced her commute during rush hours, and looked for viable back street ways of doing things. She readied extra portions of stuff, and made sure that she was well stocked with snacks that the kids could handle themselves (apple sauce, those fruit veggie pouches, long lasting fruit (apples and oranges), crackers, pretzels. She made freezer meals.
My SAHM friend was similarly sized to me, I loaned her 5 suits and a handful of shells. She made these last 3 weeks by mixing and matching. By that point, she had a better idea of what the office required, and was able to shop to update her work attire.
In addition to child care, figure out who your back up provider will be in case your kid is sick, needs a lift to the doctor, etc.
took her about 21 days to get initially acclimated, 3 months to feel like she was nearly on top of things.
Best,
F. B.
PS-
By way of addition. You might want to ready your kids. Tell them that you are going back to work because you want to. Because working is important to you and to your health and wellbeing. Explain that there will be some changes afoot, you think they are smart and clever and will embrace the excitement, grow, and change into more independent self sufficeint people.
Let them know, in a way that they might understand that if you are happy and fulfilled, you will be a better parent to them.
Also, declutter, your house, your mind, your schedule. Never hurts to come to change from a place of simplicity and strength.