What would happen if...

My first brew attempt and I think I messed up the amount of water I'm supposed to use. The recipe was 5 gallons and I only put three in bc the recipe said to do so and add the remaining 2 gallons after the wort goes into the primary fermenter. My problem starts there..I did not put water in until the next day after some CO2 bubbles started coming out the airlock. Is that bad?

my guess is that you will be fine. the things I would worry about are sanitation, oxidation, and mostly temperature. Was the water you added roughly the same temp as the wort in the fermenter? I would think you could shock the yeast if it was too hot or too cold.

It's fine! Like the trout said, sanitation is your biggest concern. Oxidation could be an issue with just dumping the water and letting it agitate so that air is introduced, but that early in the process oxygen is good anyway.

It's beer. As long as there is enough sugars in the wort and there is yeast, there will be beer.
The biggest disadvantage of the late water addition is that it could have been used to help bring the boiled wort down to pitching temperature faster.

My only concern would be...What kind of water did you add? Hopefully it was boiled or bottled.

RDWHAHB. All is well. Nothing to worry about. Cheers!

You're fine. Early on in fermentation, yeasts use oxygen to multiply and consume malt sugars. You might stress the yeast a little bit if you used very cold (or very hot) water that's more than 10 degrees f. from the temperature of the wort. Bottled water is a great choice for top off water.

I boiled a about a gallon on water and cool it to the temp of the wort. My only worry is that I made a 5 gallon recipe but only have 4 gallons of water in the bucket..I didn't want to add too much water during the primary fermentation.

This just means you'll have a higher gravity starting fermentation. It will change the profile of the beer but it will still be good.

It's been almost 4 days and I haven't opened the bucket since I put the water in. The airlock was making alot of noise when the CO2 was being released and I haven't heard it much recently and was wondering if I'm still ok. The temp is btw 60-65.

Relax, the most active part of fermentation will probably be past by now. Give the yeast at least another week to clean things up and then take a gravity reading. It should be close to that listed as final gravity (F.G.) in the instructions. Then wait 2 or 3 days and take another reading. If they are the same it will be OK to bottle. If they aren't the same, wait another 2-3 days and take another reading. You'll be fine.