You can do it right now, but should keep your garden far from the house. Something over 6 feet or 2 metres is good. The water you add to the soil will be attractive to termites, so the further out the better (but not so far you can’t nip out for a herb). If this doesn’t work for you, grow your garden in raised tubs that you can see underneath.

Make sure that you don’t dig up the termtiicide-soaked soil. If you dilute, damage or remove the volume of poisoned soil, you may enable termites to enter.  This is a bigger risk if your termiticide was a repellent one, like Bifenthrin, as the trmites can easily detect where there are gaps.
Leafy greens will often take up toxins from the soil and some termiticide sprays (like imidacloprid) are taken up by plants. That’s good if you have aphids, but but maybe not so much if you have termites.
Most perimeter sprays aren’t much good after 5 years, but it is still best to leave them until your regular inspector says you need more work done.