I wouldn't give autos any nutes, there isnt enough time for a proper flush IMO. I would just make sure my medium was rich enough to support it for the 70 days or however long it takes to grow. And I DEFINATLY wouldnt give any nutes before 6 weeks to any plant, remember your soil has enough nutes for at least the first month or so and that leaves 35 days or so untill chop. A proper flushing takes 15-20 days. That leaves like 2 weeks that the plant COULD use the nutes your giving it. And that is cutting it awefull close. Unless your growing in sand your soil should support 90% of the auto's life. This is just my opinion though, as I dont want ANY chems in my herb.
i don't think autos are different than any other plants. I do agree that it's better IF POSSIBLE to provide its food from compost soil, but this isn't always possible, and not every soil can sustain a plant very well for longer than 3 weeks.
a proper flushing takes about 30-60 minutes. well maybe in such bad cases it would need more flushing waterings, but even just one is better than nothing, and definitely helpful to save this little plant, especially in such a small container (and of course transplanting to a bigger one is quite necessary now)
one thing for sure though, no matter how organic you grow, you will ALWAYS have chemicals in your herb. Your herb is made of chemicals, and the only difference between compost, organic ferts and mineral ferts is the way you give those chems to your plant. In the end, the molecules are the same molecules.