It's up to you. Typically, most customers want to get RME up and running first. RME handles your configuration archive, inventory, software management, and syslogs. By default, RME will auto-manage all devices in DCR, so once they're discovered, you should have inventory collection already done. The next step will be to go to Common Services > Device and Credentials > Device Management, and edit the device credentials to add telnet/SSH credentials and SNMP read-write credentials. Once that's done, you'll be able to archive configs in RME.

All of this and more is outlined in the LMS 2.6 deployment whitepaper at http://www.cisco.com/en/US/prod/collateral/netmgtsw/ps6504/ps6528/ps2425/prod_white_paper0900aecd805441cd.pdf . Go through that guide, and you should be good to go on getting started with LMS.