Move live SQL Server database to a new server
since you are using SQL Server 2008 Web edition, your best bet is to use LOG SHIPPING.

Your database size is 100GB, so initializing the secondary from a backup should be considered. Dont use GUI to set up initial logshipping.

SO your steps should be :


Backup 2008 Web edition database and restore it on 2012 enterprise WITH NORECOVERY.
Launch Logshipping wizard and make sure to select secondary is already initialized. Configure logshipping to be every 1 min(this is the minimum you can get).


Move all the logins, Jobs, SSIS packages.


During the switch to new server :


stop all the webservers connecting to the database
stop all the backup, copy and restore jobs of logshipping.
take a final Tail log backup and restore it on secondary WITH RECOVERY.
Sync the logins.
Change the web.config of the application to point it to the new server. This way you dont have to change the IP address of the new server to match the old one.


I have given the post restore steps in more detailed manner here.