This is my first time stalking Southwest from the initial release window. We had never traveled at the high times on Southwest until last year, where we had to change a trip last minute from Memorial Day long weekend (prices were low when I randomly decided to book, not stalking the prices morning of the release) to Easter Week (prices were SKY HIGH as we were only about 60 days out when I switched). Knowing what I paid on the increase, I committed to making sure I booked the morning of the release this time around, thinking that would be the best I could do.
So for our trip down (initially supposed to be April 3, Good Friday), I got up that morning in August a few months back and logged on at 6am to book what I thought would be ~120 one way tickets from Long Island to Orlando for the flight I wanted (first direct flight down - last year it was a 6:20 departure). Wow - not only did that flight not exist, prices for the cheapest fares were already into the high 200's for indirect flights and either 300's or already out by the time I actually logged on around 6:25 for directs (and with 2 young ones, indirects were just not an option) - I wound up just booking on the day after (Saturday April 4) in the mid afternoon (yuck) because those were 240 and for 5 tickets it made enough of a difference (actually booked it as 4 + 1 because my wife told me after the fact that my MIL wanted me to just book for her too).
I literally haven't stopped checking since - and after rebooking the 1 at $190 when I found that fare, and then getting the other 4 down to that level after I randomly found the price had dropped again, and then finally getting all 5 down to $160 on Halloween night (so a Friday night), I then logged on yesterday morning at 6am to get my return flight (Saturday, April 11), hoping for the last direct flight back, and found that fares were $160 when they were released (and lower for different flights if I had chosen, say, the first direct flight back, which was 112/person).
Which is all to say - it really depends. I had horrible luck on the first booking day for the flight down but then great success just randomly checking 2 or 3 times a day getting the price down to a good point. And then the next time, I had great luck with doing it when the flights first popped up (I noticed by last night there were no more Wanna Get Away fares left for my flight already - surely they'll come back eventually, but knowing its unlikely we'll take another trip in the next 6 months on Southwest, rebooking was really not an option on the return flight).
So, my moral is - if you haven't booked yet, don't panic - if you think you'll use the credit, book the price as it is now and just be really diligent about rechecking. If you can't use the credit, just be that much more diligent about rechecking - even the busiest times (spring break for all of Long Island the week we booked) will go down at some point, if you're lucky enough to catch it.