I have just discussed this point a few threads up, and it seems the best thing to do is arrange your itinary to send to CAI BA office and make up the dates, changing the dates if needed costs nothing, if you do a search you will notice it's not so easy to change tickets etc as you go, especially ones issued through CAI,
I also called Ms Sobhi the other day - and she wouldn't really let me book a open ticket, and wanted the itinary faxed to her.
She didn't even want to give me a price, kept asking for the itinary - so keep it simple i say.