A little tip from me.
I find that if I WBTB, usually naturally at the end of a dream (end of REM), I can't then LD until the next scheduled period of REM comes round. My sleep cycles are typical at 1.5 to 2 hours long, so later in the night the REM is about 1/2 hour long.
This means I have to wait for between 1 and 1.5 hours before the WILD works and I LD.
The difficult bit is dozing without going to sleep. If I go to sleep I almost always just have another standard dream, and wake up at the end of the next REM, very frustrated!

So, don't be too concerned if you have to wait that long. It just takes patience.

I guess a better way would be for me to wake after REM, set an alarm for 1 hour, go back to sleep then try to DEILD. Trouble is I have a sleeping partner who would not be best pleased with that.....