There are many ways to wash it off, and keep it off you etc.
Urushiol, the active oil, is... well, it's an oil. So think of it this way. If you got a little motor oil on you or your clothes, what would you do to get it all off? Everything you and/or your clothes touched have now got it. So you wash everything. Brake cleaner, carb & choke cleaner, ether, are all pressurized cans of things that will wash it off your skin and tools in the field if you feel the need. Some of those aren't necessarily good for you, but they save you from the oil in most cases. Also, one field that has had LOTS of research and competition in removing grease and oils is... Liquid Dish soap... Dawn, Palmolive etc are all good degreasers, use them thoroughly when you get home. I normally just take the bottle to the shower with me the instant I walk in the door from cutting wood where I know there was PI. Some people say that the oil can still be washed off up to 8 hours after contact, I personally wouldn't believe that it has to be done within 10 minutes, but 8 hours seems a stretch too. The sooner the better, if you're severely allergic 10 minutes may not be soon enough, or you could go a few hours, if you're only mildly allergic 8 hours may be ok for you. For me, I just do my best to stay out of it, and get washed asap after cutting. I normally just cut after work so I only have a couple hours contact and then get it washed off.
Also, sweaty clothes will suck the oil right through to your skin so if you're really allergic don't go cutting when it's hot out in just a t-shirt. Wait until winter when it's cooler and you have more layers on.
More tips:
Because boots don't take kindly to washing, I keep a separate pair of boots for cutting wood and other activities that may put me in PI. Those boots are treated like hazardous waste around the house (don't touch them unless putting them on or taking them off), and they're only used for activities where PI is likely so that I always wash up really good when I return.
Gloves are treated the same way, but those do occasionally get washed.
When I return I strip down in the garage and put all my clothes in a large bucket/basket. This helps in 2 big ways. No 1, my wife can just take the bucket and dump it into the wash without touching the clothes, and it stops the majority of the contamination at the door to the house.
Do I still get PI? Occasionally, I do, but normally it works pretty good. There are cases where I've pretty much rolled around in it cutting and didn't get a single speck, but other times when I didn't even know I got into it and didn't decon very seriously and got it pretty good. The latter just happened a couple weeks ago, just had a couple plant on the ground that I saw so I was very careful to stay away from it, so I didn't take my decon seriously and ended up with a little on my arms (nearly healed up now).