Thank you for writing.  This is such a common problem.

Blight lives in the soil and bounces on to low leaves-- from there the rest of the plant gets infected.

https://extension.umn.edu/diseases/early-blight-tomato#:~:text=Early%20blight%20is%20one%20of,in%20sunscald%20on%20the%20fruit 

Here is my system. Buy blight resistant tomatoes

Keep the bases of the plants mulched to decrease splash up. 

Water from below, not by a sprinkler. Rain happens, that is OK.

As my plants grow, I prune the lower leaves at the stem so that no leaf gets to the ground like yours did.  My lowest leaf tips are six inches off the ground. Dont let the plants flop to the soil.

Clean your cutting tools between plants (see below). Aggressive cut diseased leaves and branches away.

Your plants are not doing well.  I would toss them and the soil and start over.  It is only Mid April.

I hope this helps.

Blight is common. It could have come from your hands touching other pots or soil, a trowel, etc

It early.  You will have lots of tomatoes this year.  Be sure to get a mix of early and late fruiting plants to extend your season.