Not too late. If you were in my area, it might still be too early. Being in zone 8, you probably have a long growing season. Looks like your average first frost date isn't until well in to November. PLENTY of time. Squash are quick germinating. Just be sure it doesn't go in the ground until the soil is well warmed up. 90 days to maturity means from when they sprout (just a few days after planting), it is three months until the first ripe fruit. You have twice that long, so you will have a long season of harvesting squash, if all goes well. 90 days is quick for winter squash.