Dahlias - pinching out

[Minkyscamp]

I'm new to dahlias, but have planted several from tubers this year. I read I should pinch them out when they reach about 12-18 inches tall, however I noticed yesterday that some of them have already got their first flower buds. Do I pinch them out regardless (flower bud and all) or have I missed the boat to pinch them out?

Thanks

Hopeful bump...

How long are the stems? I would still pinch out if the stems were long and wouldn't worry too much about a few flower heads.

Thank you. Overall the plants are about 12 inches now, and the flower stems are only a couple of inches. Maybe I'll pinch then anyway then, just feels mean!