They have plenty of time to make a queen. I made a split last week in expectation of getting a local queen, but when it fell through (after I made the split!), I just made sure the queenless hive had eggs/newly hatched larvae and they went right to work - 4 queen cells capped. Also, Same thing happened to me last year and the introduced queen disappeared, the first queen that they raised after that disappeared, so I gave them another frame of eggs last ditch before I just recombined them, Third time was lucky, but she didn't star laying until August 11 - but they built up and overwintered fine.