It will appear on RTT before next Saturday.
Probably not too difficult to guess by looking at what it might follow or where the gaps in the timetable are to do the reversals.
For example, on the first stretch:
It departs at Victoria at 0902 - there is a Dorking train from Victoria at 0855 and the tour isn't going to get to Streatham South Junction before 0909 in time to go in front
https://www.realtimetrains.co.uk/service/gb-nr:L29244/2022-05-14/detailed
At Billingshurst, the gap to reverse looks like it is after 1045
https://www.realtimetrains.co.uk/se...22-05-14/1005-1105?stp=WVS&show=all&order=wtt
and so on.
Yes, and there's a 09.56 Bognor Regis-Victoria, which arrives at Horsham at 10.41 and departs at 10.50, arriving Three Bridges at 11.03. Obviously the tour would have to follow that, so my guess would be, say, depart Horsham between 10.55 and 11.00, arrive Three Bridges about 11.05-11.15.
There is then the 09.19 Bedford-Brighton, which arrives Three Bridges 11.10 and departs 11.11, arriving at Brighton at 11.43. Assuming that the tour has to follow that one, my guess would be depart Three Bridges about 11.20, arrive Hove 11.45.
The 10.29 Portsmouth Harbour-Brighton gets to Hove at 11.45, departs 11.46 and gets to Brighton at 11.51. I suppose there's a chance that the tour might be able to get through between that one and the 11.56 Hove-Brighton shuttle, but if not it would have to wait for that one and maybe even for the 11.42 West Worthing-Brighton (dep Hove 12.09).
If my calculations are about right (and assuming that nothing goes wrong on the first leg of the tour), then about 12.00-13.00 or, say, 12.15-13.15 at Brighton would be a good guess. Chasing railtours does often involve a certain amount of guesswork, though.
