Just so that I don’t forget, here are the working combinations for WordPress Drip and WishList Member…
Assuming you’re using WP 2.9.2 or even WP 3.0:
WishList Member v2.20.435-2
WP Drip version 1.8C
As for the timezone of your webserver…
Use the Los Angeles Timezone.
Also, timestamp your backdated posts at around 2am…