A week before Get your bike (and equipment) and spend some time getting used to it. After riding it, you might decide you want the bike set up differently – adding a pannier rack, for example, or replacing the saddle with a different one, or moving the handlebar into a different position. Your bricks-and-mortar retailer can make these adjustments if you're not comfortable doing them yourself, but there may be a waiting list for maintenance jobs.
The weekend before Plan your route and ride it so you know what it's like and how long it takes. Don't just take the route you’d drive. Cycle commuting is generally more pleasant on minor roads, backstreets, towpaths and cycle tracks. Visit cyclestreets.net and use the online journey planning facility or download the free app; it’s available for iPhone, Android, Windows Mobile and Blackberry. Look for the Balanced or Quietest route options. Google Maps and its associated app also have a cycling option. Route-planning apps are good but not infallible. They may fail to factor in things like one-way streets or surface conditions; what looks like nice bridleway on a map might be an unrideable muddy track. So when you’ve plotted your route, or a choice of routes, do a recce on the most promising one(s). The weekend is ideal: you can time your journey without any pressure. Don’t race. You want a bit of slack in your schedule to be sure you can cycle there comfortably within a given time.