Go by "feel"
When my overall "system" no longer feels sick (there may be some congestion or pain lingering, but energy returning), I go back and start slow/light ASAP. If I get woozy/lightheaded, I'll back off intensity (which should already be low) or abort workout completely. The next day or next planned training day, try again, assuming I haven't regressed due to pushing too hard on previous attempt. If you feel drained or woozy/lightheaded, you're not ready IMO.
This may not be the wisest approach, but it "works" for me...and it sounds like you are similar and want to get back at it NOW.