Always start the LBC program first, before starting any of the computers cycling. Once LBC is running, you can start the LBC cycling (via the Start buttons), then the host computer cycling, or the host computer cycling, then the LBC cycling. It doesn't matter as long as you do them both reasonably close together in time.
The best way to stop the LBC cycle when the VMG or OSL is in the loop, is to stop the OSL and VMG cycling first. Then, when LBC sees those computers stopping it will stop its cycle automatically. For now, it doesn't really matter with the Macintosh, which you stop first.
If you want to stop the cycle for a short time, then re-start it, perhaps after moving the telescope to a new region, you can simply Stop the LBC cycling while leaving the OSL, VMG, and Mac running. They will be in a suspended state, waiting for LBC to say it has the light. Once you wish to get going again, Re-start the LBC cycling and the host computers will pick up where they left off.
You can also stop the LBC cycling, then stop the host-computer next, but the above two options should be used whenever possible. They just work a little more smoothly.