Hi there,
Nice to 'meet' you and welcome to the job, I'm sure I can be confident in assuring you that you will always find great support hear on the board. Based on the fact that you have actually gone to the trouble of really reflecting on your course of action and haven't just thrown all your booking procedures out the window in desperation to secure the booking, I would strongly advise you to absolutely NOT reinforce or 'reward' this, or any other potential clients disregard of your booking instructions, by allowing him to advance arrangements by text, in this way, rather you should take this opportunity to really reinforce, in your own mind, as well as publically, your boundaries and authority over the situation by implementing a strict 'no exceptions' policy, right from the very start. I really admire you for the presence of mind and self confidence you have shown thus far, in not crumbling and allowing yourself to be easily manipulated, considering your status as a complete 'newbie', and as such my advice would be to capitalise on this early success by following through all the way, hopefully setting a real president for your future endeavors. Perhaps the way I would play it would be to compose a generic text message to save in your phone, a message simply explaining to the sender that you either can not receive or do no read text messages and warmly invite correspondence via x, y, z medium. Send this guy this message, save the text to use in all future situations of the same ilk and if you like, email this guy to explain you think he may have contacted you but can he email any messages as you don't receive texts. Something like this that works in the exact context of your situation.
Anyway, I think it's always beneficial to be somewhat cynical in this game, particularly to protect yourself as a newbie, as many guys actively seek out girls at this stage in the hope of using her lack of experience to their own advantage. This is a good enough reason alone, to start firm in your insistence that bookings be made in the manner requested. I came to the conclusion, that any mature, reasonable human being would really find it little strain to follow one or two most basic requests hen seeking to secure the time of another person in the nature of our work. It's not too much that you are asking, never allow anyone to make you feel that it is.
All the best and know you never have to be alone with anything that may arise, you'll always find an empathetic ear, here :-)
xxx