It can be very exciting to enter US after you get H1B visa stamped on your passport. But, the fact of life is that you cannot enter US whenever you want to enter US. You will need to wait for certain time before you enter US.
How soon can you enter US after H1B Visa stamping ?
You cannot enter US anytime before 10 days of the start date on your H1B petition. You can see the start date on the approved I-797 form or H1B approval notice. As per USTravelDocs ( see below), you cannot enter US before 10 days.
You can totally get in trouble, if you try to enter US before that date. You may be asked to go back at the Port of Entry, if you try to enter US before that.