As it was stated in another thread, 1000TT with CPL, Multi-IR and frozen ATPL is the MINIMUM requirement for DESO. Yet, applicants generally will not be invited for interviews for DESO unless have 3000+ TT with 1000+ multi-engine turbine time.
Regarding the average experience of a successful applicant, you can refer to here:
http://www.pprune.org/forums/showthread.php?t=153757