Ripening Bullhorn peppers problem.

I'm growing some red and yellow Bullhorn peppers for my niece and haven't grown them before. They're looking good and have quite a few long green peppers but they're not showing any signs of ripening. Is it just a matter of time or were the seeds wrongly packaged and are supposed to be green ones?

My sweet peppers are slow to ripen too. I just leave them on the plant until the night time temps start to drop.

Thanks for that info.