how early in plant's life does it produce usable small potatoes?

This is only my second year of growing potatoes so I am still on the steep learning curve.

Apparently I missed a few small fingerling potatoes last fall. They did not sprout until after I'd planted tomatoes in that space. Being congenitally incapable of killing a perfectly good plant unless it is totally inevitable, I left them there. But, it is now being borne in on me, as I look over the garden, that there's an awful lot of potato biomass growin' awful close to some of the tomatoes. They will need to Go.

My question is, at what point in the plant's growth cycle do usably-sized-though-small potatoes start to form? Like maybe 1" diameter I'd probably consider minimally-worthwhile. Does this happen before flowering; or when buds appear; or when flowers open; or after flowers are over; or what?

(Trying to decide whether to keep the potato volunteers a leetle bit longer and try to pry a small harvest out of them, or just write 'em off and cut them off at soil level so's to give tomatoes more light and air and root run, without actually disturbing the tomato roots)

Thanks for any advice,

Pat

Even before potatoes bloom, I've reached down in the dirt and pulled up perfectly yummy small new potatoes. However, I only grow white potatoes and have yet to try other varieties so it may not be true for them all. However, tender new potatoes are creamy and amazing when cooked.... I've never had such WONDERFUL potatoes in my life. So if they are there for you now, get yourself a bucket full and roast them or boil them and slice them for a fry. They will be to DIE for!!!

The "standard" is after the plants bloom, but if they are in the way of the tomatoes- I'll bet you'll find some usable potatoes, now or whenever you decide to pull them. I have a bunch growing among my garlic- for the same reason. I'll be digging them up when I harvest the garlic in a couple weeks, so I can plant some bush beans.
If the potatoes are super tiny- I would just cook them with the skin on- they are way too delicious to waste!

Hokey doke -- from what you say, it sounds like it'd be worth the disturbance to the tomato roots to go prospecting for small potatoes. Will do! Thanks!

Pat