I agree with all SmokingEdge said above, but will add info for the 15 to 30 day timeframe. He has good advice for diameter, etc, and cooking temps.
1. Cure 1 is used for things That are done 15 days or less. If process longer than 15 days, cure2 ensures ongoing nitrite is produced to continue protecting meat.
2. You need to read Good books like Marianski, and follow good recipes. As smokingedge said above, the nitrAte requires bacterial action to convert to nitrite, and they don't do well at low temps. So with cure2, you need to be sure you're drying at reasonable temps above 45f, up to 53 or so. This ensures bacterial reduction to nitrites.
3. That gap between 15 and 30 days... so long as your product was held 45 to 55f so nitrate conversion happens, you are fine after the 15 days and before the 30 days, it will have been reducing the whole time, slowly.
HOWEVER.... it doesn't need to be an issue. If your product is sufficiently dried at say 20 days, and you're worried? Stop the drying process, stick it in a bag in fridge. Some conversion bacteria already exist now and will continue to work.
Don't fry your product at high heat, as smokingedge says, and the issue of nitrates is rendered moot.
Concerning eating/tasting product with cure in it... if it had a cure accelerator, then cook it up. If not, then yeah, youre eating a bunch of nitrite/nitrate. But again, if you followed correct recipe, the amounts even on day1 raw, are within usfda guides (if not dry rub curing). And maybe your celery has more, who knows what you're eating. This is like the current troll-bait question... just go watch the video at 2guysandaCooler, and make your own decision based on the excellent info he presents...
... there will be a bunch of dudes here with anecdotal " my grandpa smoked 5 packs a day and ate raw cure2 lunch and dinner, and lived to 120!", or "it never hurt me yet!". Decide how you want to weigh their input vs. the usfda etc, and make your own call. Discussions have all turned to cr@p on this, so far. I like
SmokinEdge
advice on it above for temperature etc.
If you're worried, you can add vitaminC at 1g per kg meat, so like 1/20th of a tablet for a meat patty, ground up with a bit of water, to accelerate the cure in your tasting patty, it does both nitrates and nitrites. And don't hard fry it up like bacon. Takes you about 45 seconds to do, problem solved.
Best regards, hope that input helps ;)