2-3 weeks might be a bit young, in that case the soil might be a little too hot. but you can try and see how they react. usually I only add the chickenshit to my 2 last potsizes(12 litre buckets and 40 litre washbuckets), I think I plant them out around when they are 6-10 nodes tall(I never keep track of the weeks, but instead count nodes, imo more reliable since how fast they develop is temperature dependent, and height is deceptive since they can stretch more or less depending on the amount of light they get, so therefor I go by the amount of nodes on the main stem)
there should be plenty nutrients after a few weeks, the chickenshit alread has some immediatly available nitrogen, last year I had one plant that was particularly sensitive to nitrogen, and after planting out in freshly mixed soil it already got very dark green leaves and clawing, so imo it's not really needed to let the soil rest for long.
I have no idea what my yields are in weight, since I've never weighed my harvest.
but it does depend a lot on the strain. last year most of my plants were from a cross with kumaoni(a north indian landrace), and those were pretty low yielders. I had one plant from another cross that easily yielded double, maybe triple the amount from each plant of the kumaoni-cross of similar size(there were also a few in smaller pots at another location, which were a lot smaller, so even lower yield).
that one plant was my best yielding plant last year, it filled one big mason jar(about 20 cm tall and 11 cm wide).
I've been smoking from my own harvest since september I think, maybe augst, and I guess it'll last a few more months, and I smoke every day. that's from all balconyplants+guerilla combined though, although guerilla clearly yielded less(that one best yielding plant on the balcony yielded about as much as all guerilla, around 20 plants, combined).
the year before that I had 2 plants, which kept me supplied for around half a year. my best yielding plant(a hfh hashplant2) that year yielded 1,5-2x the amount from my best yielding plant last year(I remember that same big mason jar was filled to the brim, and I needed a 2nd to jar everything) .