Good question. I spent about 8K hours in the front end of airplanes and had a handful of bird strikes, Thankfully none that shattered the windschield or into an engine, though a couple that cracked the windshield. Another that put a one or two inch dent in the wing. All of that at pretty low speeds, like 150-175 knots or slower. When approached dead on they usually follow the airflow and you get a glancing blow. A direct hit and higher speeds and they will penetrate the aircraft. I recall a T-33 took a direct hit with a large bird at about 230 knots and the bird ended up at the pilot's feet. Also astronaut Ted Freeman was killed in a T-38 when he struck a bird, I believe he was flying in the Houston/Galveston area, so probably 230Knots+ and likely a seagull size bird.
At low speed and dead on, you might get a 1 second warning, and maybe a chance to duck under the control panel, though there's not much protection there.
The risk of bird strikes is one of the reasons for the 250 knot speed restriction below 10,000 feet. Also windshields are thick, really thick, and heated. And supposedly the heat makes them sort of pliable so to prevent the birds from penetrating. I've yet to hear or see anything to prevent them from flying into the engines, except actions taken by the airports to monitor for bird activity and delaying takeoffs, or firing some sort of air canons to scare them away.