If an atomic bomb was about to go off would you feel anything?

Very much depends how close you are.
With modern weapons it is unlikely you will get much warning other than perhaps sirens from your region's early warning system (if it has one)

If you are ground zero upon detonation you will be killed pretty much immediately. It's unlikely you will feel anything and even if you did it would be so brief that it wouldn't matter.
At that distance you will easily be inside the fireball. The combined heat and overpressure would not leave much left of you to find, if anything at all.

beyond ground zero the time between the heat flash and pressure wave widens the further you go. A good distance from the fireball you will see the flash and be burned first, with the pressure wave reaching you shortly after. level of burns can vary depending on your distance to ground zero and your position. generally any flesh with a line of sight of the fireball will receive immediate third degree burns. (this tapers off the further out you go.)
The lethal range of the pressure wave itself is less than you would imagine, but it is still strong enough to cause severe damage and you would easily be killed or wounded by debris or buried under rubble.
There would also be many fires triggered by the heat flash and structure damage. The potential to be killed even after surviving the initial blast is high here.

If you are far enough away from ground zero to easily survive the heat and overpressure, you will likely be exposed to a brief but intense radiation flash that can lead to health issues and cancer at a later date. This may or may not be lethal to you depending how lucky you are.

The effects and at what distances vary depending on the weapon yield, altitude of detonation and wind direction.

I'm not certain, but I have been shot and I only felt intense heat from that before i lost consciousness.

Depends how close you were i think. If you were right under it, you might hear the bomb falling from the sky then nothing cause you would be vaporized. If it was like a mile away you would hear nothing, then the brightest light you could ever see, then an ear shattering boom a moment later, then nothing because your vaporized.

One of two things would happen see a blinding light and then be no more or be far away and get sick with radiation poisoning

You'd see the light of its flash first. Probably the cloud forming, absent of sound, depending on where ground zero was in relation to you.

I expect it would depend on how close you were to ground zero. The closer, the less warning, the more instantaneous I'd guess.

Probably depend on how far away. If you were very close you wouldn’t know what hit you.

Uhhh yes you would if you were some distance away. Close up you're just vaporized.

Depends how close you were to the blast . The closer you are the less you suffer.

Depends on how far away you are from the center of explosion.

I'd hug my dogs. Maybe collect with my friends and dogs. That's it.

Vaporized..