There is no clock for a partnership. These things are impossible to predict.
Intermune is a good example. They had positive data in early 2014, raised money a couple months later. they got bought out a few months after that for double the offering price before even FDA approval. Why sell shares a few short months before a buyout? Simple - interested parties can turn up unexpectedly and quickly sometimes, or adjust the terms to where management is ready to pull the trigger.