APPLICATION PROCESS QUESTION

I AM TRYING TO GET VISAS FOR MY FAMILY OF 5 PEOPLE. WE ARE TRAVELING IN JULY. I WANT TO GO TO THE EMBASSY THIS WEEK TO APPLY. HOW LONG IS A SINGLE ENTRY GOOD FOR? I THOUGHT IT WAS 3- 6 MONTHS BUT ON THE APPLICATION IT SAYS 3 MONTHS. IF THAT IS THE CASE I CANNOT GO YET.