I always figure between 5-7 minutes per stop.
That would give you the following from the Poly...
GF: 3-5 minutes (this is less since you do not have to wait for the complete load/unload cycle)
MK: 8-12 minutes
CR: 13-19 minutes
TTC: 18-26 minutes
complete loop back to Poly: 25-30 minutes.