theres no straight answer to how often to contact. so dont put too much weight on it, dont get worried about it.
part of the problem is that sometimes they dont know themselves. what is not enough one day will be too much the next. its fickle.
you will need to just learn as you go. try less contact, and see what it gets you, then slowly increment and pay attention to his responses and try to find the right amount.
in the beginning keep it about the kids, and let him lead. if he offers more, then take it.
just always keep in mind that he may also be confused.
sometimes you have to let him miss you.
in all of this, the only control you have is over yourself and your own actions. do the best you can for yourself, and accept how he responds. it may or may not be how you would like, but you'll end up a better stronger person.
"In a ham and eggs breakfast, the hen is involved, but the pig is committed".
