Today is day 5 - and I think he has it figured out! We had a trip out of the house this morning. He used the washroom before we left, and he didn't have an accident while we were gone. I asked him if he needed the toilet while we were out, and he said no. When we got to my in laws house (1hr after leaving our home) he said he needed to pee, but it was a false alarm. However 20 minutes later he went and did great!
This afternoon, he has told me twice that he needs to use the washroom - I am so proud of my little guy!
ETA: I am not a huge fan of pull-ups or other training pants. I think that it actually HINDERS the learning process. I have used them on occasion (more at night than anything else - and twice when we went out - but only because he didn't want to wear a diaper, and I KNEW he was not ready for a trip out of the house) Otherwise, I pack 2 pairs of pants and underwear, and bring a plasctic bag for soiled clothes - although we haven't needed it just yet.