This actually happened to me.
Back in 1985 or so, we went camping up in the Ouachita National Forest. I was about 2 miles from base camp, but close to a park ranger's cabin. Got bit on the left ankle.
Biggest thing to do is keep calm. Tell you what, I'll tell you my whole story. I survived and you can, too.
I tied off a bandage about 2 inches above the bite location, but with enough play in it that it was not seriously restricting blood flow. Walked slowly up to the park ranger's cabin. Banged on the door and just got barking back. I walked on down to where some people were camping, explained my situation, hitched a ride from them and got back to my base camp.
Once I got there, I told the rest of my party, "Now, don't anyone freak out but I just got bitten by a snake and I should probably get to a doctor." Mostly everybody freaked out, but I just stayed calm and let them freak out and get it out of their system.
I loaded up in the back of a pick-up truck. We packed ice on the bite location to help in slowing the blood flow as well as to lessen swelling. We drove a couple of hours to the nearest town that had a doctor. Got there and he was up in Hot Springs for a conference. We asked if there was another doctor in town and the response we got was, "There is, but we don't talk to them." We loaded back in the truck and headed on to Hot Springs.
Drove another hour or so, got a police escort at the city limits to Ouachita Hospital (had called ahead and let them know to expect us), and got into the hospital. I puked my guts out until I could puke no more.
So, after all that, my leg swole up like something that swells a lot (hence the ice - if it had swollen any worse, it would have been even more sucktacular). I was not administered antivenin since I was actually in pretty good shape, so I just had to metabolize the venom. I couldn't walk for a couple of weeks after all of this due to swelling and intense pain in the leg. I had to take some baths in epsom salts and wear a nightgown because I couldn't get my damned underwear to fit over my leg.
Anyway, that's my story. I survived all of that, so basically, just play with the cards you're dealt and learn from the experience if it ever happens to you.
Cheers,
kk7sm
ETA: I know the snake injected venom because I was seriously jacked up for a couple of weeks after. Docs gave me a tetanus booster.