I think it is a case of taking the bull by the horns, I have found that when Monty is not around no one seems to say, right then lets go. Therefore everyone stands around chatting and getting cold.
I am not there this weekend, but if I were you I would just say right then fast group lets go. If no one follows you at least you will get some good time trial training in.
A lot of the regulars who probably instigate when to leave are likely to be racing now which may be the issue.
Hope you have a good ride, at least you won't get cold this weekend as it looks like its going to be a scorcher.
Cheers
Marek....