Inactive Yeast? No action in the wort...

I brewed up a batch of American Amber with a kit from Brewer's Best last night. It's been about 12 hours since I completed, but still no activity in the wort. This is my third batch, and usually the wort is bubbling like a mad scientist's lab by now.
What gives?
When I rehydrated and proofed my yeast I didn't see much action either, so I am hoping it is still active. It was an 11 gram packet of Nottingham yeast from Danstar, and I pitched at right below 80 degrees.
If the yeast is indeed inactive, what now? Can I repitch with newer yeast, and if so, what's the best way to go about it?

Any advice/ideas would be welcome. Thanks!

Give it more time.

- 12 hours is nothing. It can take up to 3 days before it'll really start going. Yeast doesn't always behave the same way.
- You might not see visible signs of fermentation the only way to truly know is to use your hydrometer.

If, by some odd chance your yeast is in fact dead (which doesn't happen very often), then you can just sprinkle in another packet. But don't worry, just let it sit and if you are still worried in another 60 hours, test it with a hydrometer.

As I am sure you know by now... There is nothing wrong with the yeast. Especially with low amounts of aeration, yeast always goes through lag-phase where very little is apparently happening.
It is actually a very important step in yeast metabolism where it is preparing for the journey ahead. Search "lag phase", read and relax.

unionrdr said:

Just let it go. It can take up to 72 hours for the yeast to reproduce in sufficient numbers for them to start munching. Although,ime,re-hydrated yeast pitched in the afternoon/evening will be going by early morning.
How long did you let it re-hydrate?

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I let it rehydrate for about an hour while the boil was going.

davidicus said:

I let it rehydrate for about an hour while the boil was going.

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I really think you are just fine. Personally, I found no benefit to re-hydrating the yeast when I was using dried yeast. I just sprinkled it in and never had an issue.

A mantra you will do well to remember: RDWHAHB