Squealing like a pig!

I just finished replacing my front brake pads on a 2012 Honda CRV and it squeals like a pig.
When I first get in the car my foot goes directly to the brake pedal out of habit, I press before starting the vehicle and a squeaking noise emanates from the pedal. It is surely coming from the pedal inside the car.
Once the car is started the noise disappears? Any ideas what is causing this?

Well, since the engine isn’t running and the car isn’t moving I can only assume it’s coming from either one of the brake lever articulating joints or, since it just started with the pad replacement, the caliper sliders. Did you clean and lube them when you changed the pads? You may want to pull the wheels, get back under there, and be sure everything’s moving freely.

You said it is from the pedal inside the car? If so, I would crawl under the dash and lube the pivots and and linkage points with lithium grease. If it is outside, I agree with lubing the caliper pins.

You might also try silicone spray lube (with the straw) on the pedal pivot points.

After further investigation my original findings were not fully accurate.
The noise is a hissing squeal like that of letting air out of a balloon until it squeals, and it does happen when the car is running. It sounds like air leaking when I press down on the brakes with my head under the dash.
What have I done? All I wanted to do is change my brake pads.
I was very gentle and slow to depress the calipers with my C clamp?

I would look at vacuum brake booster hose, and make sure there is not a critter sleeping under the brake pedal!

Do you have ABS? ABS pumps can be damaged if the caliper is pressed back in without opening the bleed valve. Since you were so careful, this doesn’t seem likely, but it is worth mentioning.

Check the fliud level and booster,brake pads are pretty easy to change and generally people dont get in trouble (I used to depress the pistons with my fingers,till I wised up and used a c clamp or caliper tool)sometimes people overthink a low fluid level and have too much fluid in the system when they put new pads on.

See if the sound is coming from the brake booster. Open the hood and listen as someone bushes the brake pedal. It could be the diaphragm has a rupture.