I know you'll get a lot of responses saying that 20 m is too early, but I can tell you it is possible. The advantage of training at this age, is that they pretty much will accept that this is what they are supposed to do, rather than when they're 2 and 3 and know that they can manipulate things more.
First, know that your first child will be the most difficult. My 2nd and 3rd were cake, because they saw big brother(s) going and knew what to do.
The best advice I received was to just do it. Know that it's going to be messy, stressful, etc, and don't expect any magic tricks to make it happen easily. If it happens easily, just be thankful, but don't expect it. Put them in long, fitted pants and underwear. With underwear, they'll feel the wetness and won't like it. The long pants will help absorb MOST of the urine before it gets to the floor. I covered my furniture with waterproof mattress pads. Set the timer for 45 minutes, and put them on the potty every time it goes off (adjust as you see how your child works). I used M&ms for rewards for kids #2 and #3; #1 doesn't like sweets so we used Cheetos cheese balls, just one, not a handful. If you are REALLY motivated, plan to be at home for a week, not going anywhere, and keep them in undies NO MATTER WHAT. With my oldest, he went through 17 changes of undies on the first day. We only had 6 pair, so I washed everything in my house that day. I was exhausted and laying on the floor that night when my husband got home, I couldn't even move. But, the next day was a little better, and within a week, he was potty trained. Good luck!
One more thing, disciplining for accidents does NOT work at this age. It will backfire. Just be encouraging and patient.