Update 1: Try the following if you are getting an error on the Fido website (via Chris and Adam in the comments):
To anyone else reading this, go update your email address in your Fido profile. Log-out. Login. Try and Reserve again. Repeat the process until your email address auto-propogates when Reserving, and it will work.
Fido will allow users to pre-order the iPhone 4S on Friday, October 7th at 6AM EDT, according to a posting by a moderator in the Fido Forums:
That is correct. You will be able to reserve an iPhone 4S as of October 7th online in the MyAccount and then selecting PHONE RESERVATION.
We do not yet have any information regarding the prices or the date that it will become available. I would suggest keeping posted to our website as it will be updated as soon as we receive any news.
A tweet was also sent out earlier by @FidoMobile:
Existing customers can reserve the iPhone 4S through the Fido Reservation System starting Oct.7.
The time wasn’t confirmed as 6AM EDT (3AM PDT), but since Rogers is offering iPhone 4S pre-orders at 6AM EDT, this only makes sense the times would be the same. We have yet to hear from Bell regarding pre-orders for the iPhone 4S. Telus is offering iPhone 4S pre-orders at 3AM EDT (12AM PDT).