How many days or weeks should I wait before hanging out with her again ?

Hanging out with who?  What are you talking about?

Impossible to answer your question without having more information on your situation.

In the first days of dating someone we've really hit it off with, there's a lot of temptation to spend a great deal of time together. Usually it's best to resist that temptation. A few weeks or months in the future, that spending a great deal of time together can become problematic. 

1) "I wish I could spend more time with you" is a very positive and acceptable sentiment to express. "I wish I could spend less time with you" is not. It's a lot easier to INCREASE time together than to DECREASE that time. And when the "new" starts wearing off, one or both people will want to resume their normal daily routine, want to resume spending Tuesday nights at the weekly card party instead of with the new sweetheart, want to resume spending Saturday afternoons at the gym instead of with the new sweetheart. Better to NOT put your usual activities on hold in the first place. Then there won't be any hurt feelings when you resume those usual activities. 

2) Spending a lot of time together is boyfriend-girlfriend stuff. And when two people are doing boyfriend-girlfriend stuff, are acting like a boyfriend-girlfriend pair, then there are likely to be assumptions about feelings, about commitments, about relationship status, about what each can expect of the other. If you haven't committed to being exclusive, then don't behave in ways that imply such a commitment, don't allow the new sweetheart to believe such a commitment is in place. 

In short, try to avoid creating a situation in which you will be saying "But I'm not your boyfriend/girlfriend. I'm someone you've been dating for a few weeks/months but we haven't even talked about being official. being exclusive, etc." 

I advise that in the first few months you limit time together to one date a week, avoid those long phone conversations and save it for face to face. Make that date a real date, an outing or shared activity, and not just "hanging out." Merely "hanging out" is for just friends, for sex buddies, for hook-ups. Sweethearts DATE. 

Dates don't have to be costly. And it's OK to hint strongly that the sweetheart is expected to contribute, OK to decline to pay for "upgrades" like refusing to allow a coffee and donut date to become a "buy me steak and eggs" date. But if you're romantically interested then COURT and WOO the lady instead of merely pursuing her.