My feeling is that you are being a bit too optimistic hoping that hogs are that easy to predict! I think there are just too many variables and that it would be a complete coincidence if they followed the same pattern two years running.
They don’t normally disappear to find a mate. The courtship seems to go on in full glare of publicity although they do usually seem to disappear into the undergrowth before mating happens. The attempted mounting often seen by some young male hogs is not mating. A bit more finesse is required. Seeing a courtship is no guarantee of a pregnancy either and apparently one litter of hoglets can have more than one Father. The following is a quote from ‘Hedgehogs’ by Pat Morris.
” … conception falls well short of a sure-fire certainty. Many females still fail to become pregnant, even after several matings, and a fair proportion may escape becoming pregnant altogether. ….”
All in all, I think you are going to have to wait to see what happens!
The females do tend to disappear when the young are born. I imagine not wanting to leave them untended when they are tiny. I don’t know at what stage they choose/make their nest, but would imagine they would do it towards the end of their pregnancy(?).
Fingers crossed that the Mum hog there will produce youngsters at some stage this year and that you can enjoy watching more hoglets.