We've tried a few things and often find we give people too much information on their first couple of days.

We've started to design a modular system of info chunks that get emailed to new team members through out their first week (through a Mailchimp drip campaign). This way they don't have an information overload on their first day. This takes a lot of responsibility off someone to give ALL the important details and lets them get someone up to speed at a more manageable pace.