Keep a detailed record of your insulin doses for the week leading up to switching to a pump, to start you off they'll likely enter one basal rate into the pump until you get round to doing some basal testing, the DSN will deduct 20% from your current basal usage on injections as most people find they need slightly less basal insulin when using a pump.
The first day I went slightly high but I think that was down to nerves, after a few days I started basal testing and by the end of the week was using 3 different basal rates, currently using 5 but doing some basal testing again this week as I had a couple of lowish readings last week and need to review things again.
If you've not read the book Pumping Insulin by John Walsh & Ruth Roberts then I recommend you do, it goes into great detail about basal rates and getting the most from an insulin pump. Good luck and hope it all goes well.