Upset and mad at myself

I am a new diver and when I got out of the salt pool to clean my reg off, I forgot to put the dust cover on. I didn't realize this till I got home 3 hrs later. Have I ruined my new reg already. I am supposed to go diving in the AM

You're fine... rinse it out... (don't submerge the 1st stage, unless it's attached to a tank)...
That's no problem at all... not enough time's gone by to do any damage...

So just dipping it quick in fresh water for a few seconds maybe didn't hurt it.

If you rinsed it in fresh water you should be fine. Just plug it into a tank and air dry it.
Hold all the hoses higher than the first stage and make sure all water has drained out first.

You can take it to a shop and have them open it but it should be fine with just leaving it pressurized on a tank.
Some say that you could get water in the SPG this way which will ruin it. But honestly the hole on the HP port is so tiny that it's not likely to flush a huge amount that won't dry with air circulating through the hoses.

If it was dunked into salt water then you should take it to a shop and have them take care of it.

Thank you both

Soak in fresh water, if the reg had salt water enter it.

Then, remove the high pressure hose(s). Place on a tank and blow out any water.

Then, screw in the high pressure plug(s). Place back on a tank and blow out any water through the second stages by purging.

Then, replace the high pressure hose(s).

This is the procedure my reg tech recommended when I had a brain fart and submerged by reg in my rinse tank without the DIN plug on.

Worked just fine for me.

As above, whip the SPG off, connect to a tank, turn tank on and blow water out of the HP hose/reg for a bit. Then purge second stages. It'll be fine.

Water in the SPG IS the main concern - its a small hole but 200+ bar of pressure can easily force water through there. It lodges in the very small capillary and other parts of an SPG where if it causes corrosion, forms salt crystals and so on can lead to the gauge not working properly.

OP--They are totally wrong and your regs are totally ruined.
You must IMMEDIATELY place them in a cardboard box and mail them to the regulator disposal/crushing centre located conveniently in Auckland New Zealand.--Ill supply you the address if you send me a PM

JUST IN CASE--you think I'm serious Im kidding.
Hey folks My mental image is that the dust cap on the first stage was left off after rinsing. in my mind no harm/no foul

OP--They are totally wrong and your regs are totally ruined.
You must IMMEDIATELY place them in a cardboard box and mail them to the regulator disposal/crushing centre located conveniently in Auckland New Zealand.--Ill supply you the address if you send me a PM

JUST IN CASE--you think I'm serious Im kidding.
Hey folks My mental image is that the dust cap on the first stage was left off after rinsing. in my mind no harm/no foul

If you left the dust cap off while rinsing it may not be a big deal. Depends on the water you rinsed it with. If you dunked it then it MIGHT still be ok. As others have already said take the HP hose off before pressurizing it. WHen you pressurize it crack the valve slowly. Then put the HP hose back on without the spg. There is likely no water in the hose but why risk it. Pressurize it again SLOWLY while FIRMLY holding the free end of the hose. It would be better to do this with a tank that has already been used and is down to around 500 psi or so. Point it away from anyone! Make sure no mist comes out. Then put the spg back on. If you see water blowing out of the hoses in any kind of real quantity I'd be leery of diving it before having it checked.

As a tech and an instructor I'd advise you to have an experienced diver or better yet, tech do the whole procedure. As a newer diver (if your profile is correct) you may not know all the things to look for. Even a reg that has only seen freshwater enter the 1st stage should be checked as the minerals in some freshwater sources can dry and begin to cause corrosion over time. This is speaking not only as a scuba tech but someone who runs a waterjet cutting machine and sees the effects these things have on our equipment. Even with a good filtering system we have damage from so called clean freshwater.