The Pro-C controller will allow for only a single program to run at a time. Therefore you will have to be sure no two programs overlap.
In the Set Station Run Times position the Total Run Time calculator will help show what the total amount of time to finish a cycle is going to be for that particular program. The total run time calculator will show up after the last stations run time. After the total run times for each program are assessed the Start Times can then be staggered to guarantee there is not a program trying to come on when another program is still running.
If the Start Times on multiple programs overlap, the second program will wait until the currently operating program completes cycle before starting.