They should revegetate normally from mid-May to mid-July. After that, they'll still have time to grow again until mid-August.
They'll probably grow a bit weird, especially at first, and you'll have to do a lot of pruning of lateral shoots.
You can help speed up the process by giving them some light to extend the light hours to at least 16. It doesn't have to be a very powerful light.
Also, if you don't want to take the risk and have more seeds available, early May is (in my opinion) the perfect time to germinate, at least in much of Spain. You're at the best time to put in some additional reserve seeds.
Good luck with the grow!