I wouldn't too much about timing.. Plans can change
My H in June was telling his family he and his new girlfriend were coming up to visit them in August. Tickets were purchased.... We all know that trip didn't happen. Not saying your W won't make the trip but anything is possible. Try not to worry too much (easier said than done I know). I found that looking at shorter time frames helped.
I also know everyone is against this - but I think what helped me detach was the attention from another man. I know it goes against DB. However, for me, it was knowing someone successful, intelligent and funny was interested me. H had made me feel like dirt and my confidence took a beating. So seeing that someone could be interested in me helped. We hung out outside of work once and it was around the time right before H wanted to R. I quickly cut it off and this guy still is peeved about it. Now I am not advocating for dating because you are still married. Just the whole flirting, feeling desired, etc can really boost PMA and detachment IMO.
Also, you really should start counting OM from when they moved in together. Let them live the life of responsibility and not fantasy. H lived with his boss at the time on his couch and OW was the boss's daughter. Apparently she moved in there shortly after which only sped up the demise of the A
