@Michael596 In the case of most booking requests, before we approve the booking, we send the potential guest a friendly message that also contains our entire House Rules (not just the check-box "rules" that AirBnB lists) and ask that the guest acknowledge their agreement with the rules and our cancellation policy. We do that for two reasons: 1) it might weed out a guest who doesn't want to follow the rules or didn't pay attention to the cancellation policy, and 2) when they respond with a "Yes, looks fine" message, we have that exchange on record in AirBnB's message system in case it's needed later.
When the guest does respond affirmatively (almost all do), we approve the booking and then send them another friendly "Thanks for booking with us, blah, blah, blah, and we'll send you door code and parking info, etc, 7 days before your arrival".
Which, weeks or even months later, we do. (As an aside: Immediately after accepting a booking, I pop two entries into my iCal -- a reminder 7 days in advance to send the promised info to the guest, and a reminder to clean the apt on the day of their departure.)
I wouldn't, as someone else mentioned, wait until the day or arrival or even the day before, to send that sort of arrival information. For one reason, people may be traveling and not easily be able to retrieve the info. For another, guests tend to get antsy as the day approaches and they'll be inclined to bug you in advance anyway.
Note that our listing does not use the Instant Book feature. We get to approve or decline all requests. If that's not the case for your listing (I suspect that your newish listing has had Instant Book forced on it), then I'd still send the House Rules as soon as possible after the booking is made. Some guests may have missed some of the key rules, such as "Max 2 people" or "Absolutely no children" or "No Pets", etc, etc. In that case, after receiving the rules, they might choose to cancel their booking and go elsewhere.