I've never been a stay-at-home parent, but I've transitioned from working from home to corporate gigs on a few occasions. From personal experience, I'd avoid shocking your system too much. Avoid jumping into a fast-paced, long-hours, high-stress environment.
If an option, maybe try to find some part-time or contract work to start out. Also, try to train yourself for the transition by setting a mandatory work hours schedule, if you don't already have one. Schedule 9-5 type hours that you will focus on finding a new job or working on something specific like hubbing or whatever. Good Luck!!!