How often should a guy call in the begining...after 1 or 2 dates?
How would I know if it is getting to be serious? Should I ask him our 4th date?
I wouldn't start counting calls after one or two dates. If he calls, and you like him, make plans to go out. After one or two dates, you should be getting to know him, not pinning your hopes on marrying or "getting serious" with him.
I definitely would not ask a guy his intentions on the fourth date. It's possible he's still doing what you should be doing; i.e., getting to know an attractive new person.
You can pretty much tell that someone has decided to take things to the next level when he calls to get together as often as possible (as opposed to merely texting you or calling to vent about his day). The man will leave little doubt in your mind that he wants to be in your company.
He will communicate his affection for you clearly. If he starts thinking about commitment, believe me, he'll let you know. He won't risk letting you think he doesn't care and losing you!
In the meantime, keep your options open. Keep dating. Meet new people. Who knows? You might meet someone you like even better than this guy.
So, instead of focusing on the frequency of his phone calls and how soon you can get him to commit to you, sit back and decide whether or not he's truly the kind of person you want to spend your time with. Worry less about what he thinks about you and more about what you think about him.
Besides, if he picks up the vibe that you're focused on landing some man, rather than getting to know and perhaps developing a real and lasting affection for him, you very well may send him screeching in the other direction.