Windows wait command till a system time

I have made a batch script for backup recently. Somewhere in the middle of script I'll have to wait for some time to be reached and then resume the next line of the script. I've scheduled the script at 4:00PM and after the wait command the next line should start at exactly 5:30PM. I thought of using SLEEP command but it's not sure that the commands used before the wait command will end up at certain time(due to inconsistent file sizes) but it's sure that they will be done by 5:00 or 5:10 and next it should execute wait command which waits for certain system clock. I'm checking if there is any command that waits or sleeps until the time specified reaches the system time and resumes there after. Anybody came across this situation and how was that resolved?