WBTB is (nearly) the only way to effectively WILD. You will find it extremely difficult, bordering on impossible, without a WBTB -- unless you're incredibly sleep deprived. WILD works by slipping right into a dream from the on-set of sleep, and most importantly most of the dreams that we remember and become lucid in are during REM-periods; which occur, roughly, once every 90 minutes.

That said, by attempting to WILD without a WBTB, not only are you going through the entire process of falling asleep (which can take a while), but you won't be entering into a REM period, which may cause the dream to be very low in terms of clarity, vividness and even recall.

WBTB is definitely the way to go.

Whats your sleep schedule like?