Companion planting basil & toms

We've got a big hydroponics thingy in our greenhouse planted up with tomato plants. I was thinking of sowing some basil seeds in it as i heard they are good companion plants - should I sow straight into the bed or let the toms (they've just been transplanted about 4 days ago) get settled in first ?

no, we're not doing hydroponics, it's just a massive container. it's got compost, manure and some topsoil in it. Hubs got it off a bloke at work (seized from a drug dealer !)