I have had MANY clutches without ever witnessing locks, now I usually just go by the overall behavior of my animals for example if the snakes are both on one side of the enclosure, not a great sign, if the male is on the top of the female chances are he did or is about to do the deed.

After that is really about knowing your female, paying attention to low pressure and introduce your male when you know both animals will be the most receptive.

Some people don't pay attention and pair their animals over and over again (for too long and too often) and all it does is over work their male.

Breeding really requires you to be in tune with your animals and remember it's still very early if you use seasons the whole process is pretty lengthy.