big' time'

1. Informal.the highest or most important level in any profession or occupation: She's a talented violinist, but she's not ready for the big time.

2. Slang.a very good time.

3. Theat.(in vaudeville) any highly successful circuit of theaters that produces two performances daily.

http://www.infoplease.com/dictionary/big+time

Definition:

top level of achievement: the highest level of achievement and success in a profession or other activity

Now that you've appeared on Broadway, you've hit the big time.

http://encarta.msn.com/encnet/features/dictionary/DictionaryResults.aspx?refid=1861686169