Well for me that would be NEVER! Sorry but Jeyes fluid basically destroys the soil.

i hate to disagree but jeyes fluid as you say initialy kills all plant life but like most things these days is and has to be bio friendly infact i use it to premote greening up of my sculptures as it does break down to become a fertiliser . this was not the case years ago . i would wate till about mid summer and get a plant that doesnt matter and see if it grows . if not do it again every so often till it does grow . i strangley enough live near jeyes factory and my sister works there . i clean my dog run with it which is cement . it slopes down to the end of the garden about 40 foot wear it goes to a little 8` x 8` soakaway with a cherry tree in it with roots just under the soil and that is thriving like you wouldnt believe .

six weeks. Though why you should want to treat it i don't know, unless whatever you were growing in it had problems, in which case leave alone.
I've been re using composts for donkeys years without sterilising. Just mix in fresh fertiliser. In fact,with the rubbish they call compost available at the moment. probably better off doing that.

could of been something nasty growing in it scrumpygrat but im a bit stump to excuse the pun lol .