No I would wait until at least day 8 even if you have short cycles. If you have got the really cheap ones then really you can pee on as many as you like but the others are expensive and I wouldn't waste them. Even day 8 is early to start, I usually waited till day 10 and I tended to ovulate around day 15/16.
I would recommend actually leaving it three months while your cycles get back to regularity. You may even conceive in the meantime if you have loads of sex. Timing it to fit in with ovulation is a pain in the neck - if you go for every 2-3 days you can't miss ovulation really.
If you want to use them straight away I would strongly recommend getting the cheapo ones from the internet.