if you don't have the time to test, just collect the data for the time being, and ignore the tss/etc until later. if you're really dying to find a ballpark number for your ftp, just go do the 8 minute carmichael test (do 2x8 minute time trials, full tilt boogie, in the same ride, take the higher number of the two, multiply it by 0.9, it's probably one of the least accurate methods, but it's probably better than just picking a number at random).