Herbs flowering

[Louiseness]

I have some pots of herbs including oregano and mint, bought as small plants in June and July and growing really well. However, my mint and oregano are now flowering (well, and the thyme but that's been flowering since I got it!).

I've heard that if I wanted to dry the oregano I should cut off the stems before flowering, but will it hurt to just let them flower? Will this cause anything bad like them dying off or anything?

Also, when is best to prune my herbs to keep them bushy and encourage them to grow?