What I know , that when study starting officially you can start your work/testing.
Otherwise companies don't want to have extra cost in case FDA change something last minute.

I did a study long time ago , in Downstate University in NYC , I had few meetings with Hoffmann- La Roche before , they told me what type of patients they will need , and told me when they think study will start officially ,
But I couldn't do anything before , but I know I made a list of my patients I like to put on this study , so later it went fast...

I don't think many things change since than....