John,
Yes, we do it online. I use the clock on my Verizon phone. Sometimes we get in, sometimes we do not. It all depends on how many people are going for the sites. Also, at WP go for the higher number sites. People tend to like the lower number sites especially sites 7 - 11, so we tend to go for sites in the 20s.
Remember, look for cancellations, especially as it gets closer to the date.
I just got 8 days at Highlands Hammock state park for the end of January. Someone must have cancelled. It is about 70 miles north of WP.
Sue