We did a week after we started dating.
We were friends for a couple years beforehand and always had a really intense connection, physically, emotionally and spiritually. Due to some other factors, it wasn't right until this year. Finally, a week after our first kiss, he told me. I knew I loved him too when I didn't run away (trust me, I'm the Miss Independent out of my friends).
Yes, he shows it to me and I to him. We take care of each other when sick/stressed. We get along beautifully. We talk through issues that are difficult. We have plans for the future. Meeting his friends and family confirms what my gut's been telling me.
Of course, I told him a couple years till we seal the deal. We need to see how we make it through the next couple of years before we make it permanent (I'm going away this fall, for a year, but coming back, he needs to finish his degree). If I'd let him, he'd propose to me now, but I find it more prudent to wait. If/when he does, I want to give an honest "yes" without a single hesitation.