i think you missed the boat. not sure where you are (down south or up here) but up here you need to get the plants out early for maximum growth by june. onions start to form bulbs around the longest day of the year which is june 20-22 depending upon the calendar. not sure how that works in the south as their longest day is much shorter than ours, 13 vs 15-16 hours.

you can plant them and maybe just eat them as scallions ie onion plants with no bulb or a small one like a marble.

tom