Since no one else has answered you, I will try. I would consider the full grown width of your plants and plant accordingly. so if you're tomatoes will be 2ft wide (just a guess) plant your companions about that far away to give them both enough room to grow. I've been known to violate that when not paying attention and have still had decent growth, but would have gotten better growth/production if the spacing was a little farther apart. for example, my nasturtiums were swamped by my zuchini and yellow squash bush plants because I wasn't expecting the squash plants to get so big. the nasturtiums grew, but were very stunted and didn't really start blooming til the squash plants started dying back.

for plants that don't get along, it may be best to have another plant in between them to give them a bit of distance and a physical barrier.

this probably isn't the best answer, but I hope it helps some.

Distance may vary depending on the relationship of the companion; cooperative, attraction of pests (lure), attraction of beneficials, distraction of pests.

They may be immediate neighbours or a few feet/yeards away. The tomato & basil might be close enough for root interaction since is said to improve flavour.

I alternate companions in my 3' x 8' raised beds if they are cooperative. I try to put a lure companion in a neighbouring bed. So many of the herbs and onion family are good just to ward off the pests.

Compost tea is also a good practice.

Good luck.