Your target zone is probably pretty close to 4 am if you must be up at 6 am. Start with a very low pressure WBTB. If you do not wake naturally to urinate at all in the night then try drinking about 16 oz of water soon before bed. If you do wake to urinate naturally all the better. Use that waking as your WBTB. Try to get your timing as close to 4 am as you can. If with in a week or so of trying and not being able to time the awakening you could consider an alarm. If you do it by the need to pee, then try not to wake up much. I will go into the bathroom with lights off and do not engage my thinking any more than needed. Go right back to bed and casually and with little focus or concern (that would wake you more) try your WILD.