Personally, I think it is better to put the tomatoes in the middle. I thing you are not paying much attention to seasons in your plan. One thing that gardeners need to learn up front is cold weather crops vs warm weather.
Cold weather crops include lettuce, spinach, kale, cabbage, broccoli and others (chard and carrots are in a special category about which more later). Cold weather crops are very frost tolerant, like cold weather, and tend to bolt and be done as soon as the weather gets regularly in the 80 degree range. They are planted early.
Warm weather crops include tomatoes, peppers, corn, squash, etc. They get killed by any frost, like warm to hot weather, and cannot be planted until the soil has warmed up some. There are some degrees of this. Squash are the last to go in, need really warm weather, corn (if you are growing it, takes a lot of room) can be the first of the warm weather crops to go in.
So I plant the cool weather stuff, which in general is shorter any way, around the front edges of my beds, very early. Cool weather crops can go in the ground (either as seeds or transplants) as soon as the ground can be worked, which for me is about a month earlier than my average last frost date. Later, after danger of frost is past, I plant the warm weather stuff behind them, especially tomatoes. Then by the time the tomato plants are really getting big, the cool weather stuff can be pulled to make more room.
Back to the chard and carrots. They are cool weather crops that get planted early, but unlike the rest of the cool stuff, they are going to keep going/ growing all season. Carrots are just slow and take a long time to get ready before harvest. Chard are very productive. You can just keep picking leaves off them as needed. Unlike spinach and lettuce, chard tolerates the heat and keeps growing all through the summer.
But carrots are good companion plants for tomatoes, so I still do a row of carrots down one edge of a tomato bed.