It depends on the dosage I'd say. If you mix it, water it in, the worms will start working on it. There are some guidelines for food, as long as it doesn't physically 'touch' meaning no root vegetables in "raw" manure, or otherwise 30-90 days hot composted for root vegetables, something like that. Personally I'd try to stay away from those palleted $2 'manure' bags, but if you have something a little higher grade or closer to farm refuse, I think you can mix quite a bit into your soil volume wise and let it compost 1-3 months before planting.

Really, no fresh manure should be used on an edibles planting bed. In addition to often being too strong (high N burning tender seedlings and plant roots), there can be issues with pathogens and chemical additives in the feed that need some time to get flushed out or neutralized. "Fortunately, chicken manure is among the most prized of manures. Fresh chicken manure is considered a “hot” manure, which is unsuitable for immediate use. Chicken manure needs to be composted and aged at least two to three months before you add it to your garden. If you don’t wait that long, it will burn your plants." (Gardening with Chickens). Unless you can confirm that it has been aged several months or composted, all you can do now is just wait until an appropriate amount of time has passed before planting.

Actually the bagged stuff is safer than the direct-from-the farmer-fresh!! It is properly composted or at least aged until considered "safe".

If it doesn't smell terrible than it is probably somewhat composted. I use my chickens manure in my garden every year. It has a higher nitrogen and phosphorous content than cow manure. The thing is that it can burn your crops if not aged or mixed in the dirt to cut its strength. The stuff is good. You can throw it in a compost bin with a bunch of yard clippings and weeds and let it "hot compost" for two weeks with daily chopping and turning. That will be enough to get it settled in. At least in my opinion.

It's already been spread on the garden soil.....a bit too late to try and compost it now!

Fresh manure on a garden = bad. It's great when it is composted but, as noted, the excess nitrogen will burn plants. The nitrogen is from the fresh urine, which contains urea, which decomposes into ammonia. Plants do not like ammonia, and neither do you. The ammonia eventually gets incorporated in the soil as plant-usable nitrates, but even that may be overly strong unless some of it is used to decompose the rest of the manure.

Good point about bagged manure. With that, you have some assurance that the stuff is aged and safe.

Also true about dosage. If you just dig in a little bit, you'll probably be OK, but how much is a little bit can be difficult to assess.

I'm afraid you'll want to wait a month or two before planting, and if I were you, I'd keep the stuff moist, and stir it around, to speed up decomposition.

I feel that the problem of excess nitrogen in chicken manure is vastly overblown. Sure it has more nitrogen than cow manure, but that’s still a lot less nitrogen than popular liquid fertilizers like miracle gro which are used without any problems after being properly diluted. If you’ve already applied too much, you can just leach the nitrogen away by watering your garden more than you normally should.

The issue isn't just nitrogen burn, as I said, it's about ammonia burn (which is sometimes lumped with nitrogen burn, since ammonia carries away nitrogen). Ammonia, as a gas, is HIGHLY caustic, and will kill lots of stuff. And no, ordinary popular liquid fertilizers don't have or produce ammonia. Urea is a high nitrogen fertilizer that does produce ammonia (it's the urea in manure that does it as well) and at least in pure granular form, you don't put urea around plants.

I've dumped raw manure around growing plants, and the result is devastation.

As Dave said, tilling the manure into (moist!) soil asap is the best way to get it quickly decomposed. I think we're still talking about a month before planting, though. To decompose the urea in the manure, you need urease (which is resident in the soil) and moisture. If the manure just lays on top and dries out, you're just postponing that decomposition. I suspect the same is true for pathogens. You just dry them out, and they will re-energize when they get wet.

You could just plant some stuff and see if it grows.

Dig up a weed and transplant it. See if it gets burned. If it just wilts, that's transplant shock.