St Aug sod comes in 24x18 inch pieces. I've never seen plugs.

It should not be too late. I put down 90 pieces 2 weeks ago and they are all knit down and doing fine. I am no longer watering daily. Given what you're describing, here's what you should do.

1. Spray the area with RoundUp to kill the existing weeds.
2. If it does not rain, water the area daily, 3x per day, lightly (10 minutes or less), for a week.
3. Watch for new weed growth and spray the RU again. The idea here is to germinate all the weed seeds and then kill them off. This will make the new install go better. After the second spray you can lay the sod down.
4. Get fresh sod. The place I bought from gets and sells 14 pallets per day, so the sod is fresh. Call around to find a dealer with some serious throughput, and put the sod down the same day. Put it down like you would bricks staggering each row of sod. Walk on each piece after they are all down to press the underside of the sod against the top of the soil. Roots will not grow through the air to reach the ground underneath.
5. Continue with the 3x per day watering for 2 weeks. I have to admit I watered only 1x per day and it came in fine in 2 weeks. My wife hit it with a soaker hose a couple times, and that seemed to be appreciated.
6. After the grass is knit down, back off on the watering frequency and increase the timing. Eventually you should be deep watering roughly once every week to 10 days. Deep means 1 inch all at one time. Most Floridians want to water daily, but don't fall into that trap.