Last week, we had frost and saw alot of stuff die back but these oleanders are still flowering and producing blooms. I read online that the best time to prune oleanders is by the end of September when they're done flowering and I've been meaning to prune them cause they've gotten so leggy that without support, they just fall completely to the ground. Should i prune them now or wait untill spring or when they're done flowering?
Late flowering Oleanders like yours are actually best pruned in late winter or early spring; pruning back now if your weather gets cold may encourage new growth which will be damaged by frost. Oleanders which flower earlier usually finish flowering earlier, so can be pruned back in September, but it's too late in the year now to do them, especially if you've already had a frost. It's not essential to prune them at all - if yours are leggy, are they growing in a position with insufficient light/sunlight (it's hard to tell from the image how much light they get). Otherwise, it's relatively light pruning for younger plants, usually concentrating on removing damaged, weak or unwanted growth and perhaps shortening some stems to encourage stronger plants. Further information on harder pruning here https://www.gardeningknowhow.com/ornamental/shrubs/oleander/rejuvenating-overgrown-oleanders.htm