brew today pitch yeast later?

I just got an extract brewing kit in the mail but I didnt realize it doest come with yeast so I had to order that today and it probably wont be here for a few days. I was wondering if i would run into any problems brewing the wort today, cooling it, putting it in the carboy like normal but just pitching the yeast when it gets here

The longer it sits without yeast the higher the chance of something else, something that you don't want, to start eating your sugars.

I am sure that someone will come along and tell you that they have done it and it was fine, but I highly suggest waiting until you have the yeast.

Some people do a no cool down wort method. They brew the batch, let it cool down naturally and pitch the yeast later. I think there is a person on this forum who experimented with storing wort for several weeks before pitching the yeast without any problems. If you brew it and add it to a sanitized / sealed container you should be ok.

I did 2 or 3 batches where I let the wort sit overnight and had no problems.

I'd wait for the yeast before brewing.

Unless you can ensure that your brew is completely sanitized and 100% of your equipment is completely sanitized, and there is no wild yeast or bacteria or anything floating around in your air, you're asking for an infection.

I had to do this a week ago because the wort didn't cool as quickly as I thought and it was getting way too late to wait any longer. I was going to put a piece of saran wrap over the carboy, but just used a sanitized air lock instead. It started fermenting in less than 12 hours after the yeast was pitched (I did a yeast starter.) I was pretty PO'ed that night when it didn't cool quick enough, but once I saw the overflow tube doing its job, my worries went away.

one day wouldn't be a big deal, but if you had to order it today, i'd at least wait until you know the yeast will be there within 24 hrs of finishing the boil.

Usually you use a chiller to get the temp down to 70 as fast as possible to introduce yeast so it has a head start on taking over as the major force eating away in there. Leaving it for days allows a small weak strain of ANYTHING to grow stronger and stronger and multiply, taking over that sweet wort you made for it. This can create huge off flavors or souring or ruining your batch.