Comment 24 for bug 290136

Nevermind, it appears that the only way to do this is to create a bash script that will delay Do, and even then it will create another bash session which add (although only slightly) to overhead.

This is really a problem with gnome-session for not having the option to change the order of startup apps or being able to delay them. There are lots of bug reports on the subject. Here is an example. https://bugs.launchpad.net/ubuntu/+source/gnome-session/+bug/148605

It might be possible to add an artificial delay to Do and create an option for it in the preferences menu, but I wouldn't know how to do that.