I can't see many wives reacting well at your magical 6 month point to "hey I met someone else, been with them 6 months, it's time for the new love of my life to meet the kids".
She'll have been dealing with the kids reactions to daddy not being around, and to her it'll seem instant - her first response will be "I'm not letting someone I've only JUST heard about, meet MY precious darlings". Whether or not she says it out loud is another matter.
You need 6 months AFTER you tell her about your relationship before you think about meeting HER kids if you want to keep relations harmonious long term, as she'll instinctively need evidence that your relationship isn't just a flash in the pan. That's not spitefulness or anything horrid, just the natural desire all decent mothers have to protect their children from emotional harm.
He's only been separated nearly a year, and only with you a few months. take your foot off the gas pedal and ease back a bit. It'll give you a chance to sit back and observe. You cannot 100% say that you'll end up with this man long term yet, as you have NO idea yet how he parents, or even if you like his kids.
As someone who has been in the step mum role I honestly feel that it's only possible to make a success of a traditionally awkward role if you feel genuine affection for the children concerned -independently of any feelings you may have about your partner. You have to love them for themselves. With the best will in the world sometimes personalities just don't click and it's no one's fault. Feeling duty towards someone else's child isn't enough.
So even if you maintain your current punishing schedule, you'll need another couple of months for his wife to find out about your existence, 6 months for her to help the kids adjust to the idea of you, 6 months for you and the children to decide whether you find each other remotely likable. (It takes longer to work out if you are compatible btw!)
You can't possibly say with any certainty whether this is a relationship you would even want to be serious and committed to for at least another 18 months if you are sensible. In 18 months time your man's divorce status may or not be clear, but your feelings bout whether the relationship is worth taking to the next level will be a bit clearer.
A man doesn't have to be tom catting around to be an unsuitable partner. Your thread has highlighted for me, why I always refused to date separated men - too complex.