It's a good point but unfortunately many SPs suffer from STMS and will have forgotten what they promised you yesterday let alone 2 months down the line.
Its often not as straightforward as that though, popular SPs can be fielding 30 to 50 messages a day possibly more, remembering who asked to be contacted in advance of a tour can be almost impossible.
However its possible to set up sub folders in the AW email I believe, so setting up ones for regular locations and moving those that ask for prior warning of tours into those is doable I believe.
The other option a lot of SPs who tour use is a tour tab on their AW profile, which allows them to update and list dates and destinations in advance.
If the SP on your hot list has a tour tab the its worth checking that weekly and hopefully that will be in advance enough for you to arrange a suitable window of opportunity to book.
Am I wrong in thinking that you get a notification bar across the bottom of your AW page showing updates for those who you have on a hot list when they edit their profile, that may give you a heads up when their tour tab is updated if so.