anyone knows H2?any cap for H2

H2:An international beneficiary who is offered a job by a U.S. employer may enter the U.S. for a temporary time of specified duration to fill the offered position. The employment must be a one-time need based upon low U.S. worker availability, seasonal, or cyclical needs.

Can we apply for H2 while waiting for the quota of H1?
then transfer to h1?