In my experience, once you've signed up, you generally don't hear anything more until 1-2 weeks before the event itself. At that point the EO emails you a 'welcome pack' detailing the event itself, how to get there, expectations from you as a roboteer, where to load/unload, and any special requirements.
In my experience, it can be less than a week beforehand as well so don't be too surprised/worried if you've not heard back until Monday of that week. If in doubt, e-mailing the EO is also an option.