Fire Ants, is the next day after a bite worse?

I was gardening and had the wonderful experience of stepping on a red ant nest. I was swarmed for about 30 seconds before I fully understood what I had done. Being from the North, we don't really get much in the way of red ants. Anyway, I seems to have about 5 bites luckily on my feet and one on my stomach. I quickly took my clothes off and threw it in the washer machine and took a shower as well. I only have red marks now after about an hour. I have heard mixed results about, burns more the next day, might get blisters the next day. What should I do in order to prevent this or make it less bad? Or should I have a reaction right away normally? Thank you!