It depends on when in May you're flying - the holiday weekend or another time
FWIW, our trip is 12/13-12/21. I waited several months after they opened up the schedule to book. In fact, I booked our Feb dates, before I booked our Dec dates. For our route - BDL - MCO I thought $120 was a bit high. We had some flexibility around our days so as long as there was at least one flight at $120 that I was ok with, I continued to wait.
I finally FIRST purchased 10/17 (for a 12/13 travel date) the flights were $110. I changed on 10/29 to get them for $90, then on 11/19 to get them for $84 and then lastly on 11/20 for $66 (this fare I think was only on sale for a couple hours)
I didn't do as well with my return trip, - which I did with points,but I think I got the comparable of $84.
So if I was you, and was travelling mid may and didn't HAVE to travel on weekends, I would probably wait for now....
But you have to do what works best for you.
The nice thing about SWA is that you can change for no change fees