I’ve had real trouble getting cucurbits to grow earlier in September. In that first lot I’ve only managed 2 out of about two dozen pumpkin and cucumber plants (plus 1 weed that for a few weeks carefully disguised itself as a cucumber haha).
So in early October I planted afresh, this time into punnets as opposed to bothering with individual pots, in case they fail me again. Sure enough, they are coming up (temperatures were pretty much the same both times too, as I used a heat mat etc). Of course, now I will have to transfer them into larger pots as they won’t be planted out here until later in November. Sometimes I wonder if plants just have their own ideas, a bit like pets.. and husbands too I guess, I hear kids can have their own ideas too :D