I was totally there. I learned that the best thing to do is role model for him what he should do. To say "Oh! I'm sorry, i'm still playing with that, i would like that back please" or what have you. I also realized (a bit older though) that even when my boy was "may i have a turn please" the vast majority of other kids would ignor this request, take the toy and run... and unfort there are many mom's out there on their cell phones not paying attention or teaching THEIR kids that its inappropriate. I actually had 2 older kids corner my 2 yr old in a corner of a fort... they didn't follow my redirection and of course the mom's were nowhere to be found, it was the only time I physically removed the kids from the corner (he was physically trapped by them) to get him out. We tried the "excuse me please", and when that was ignored i said "Ok. you need to move now" and moved them. I am not sure he knew what was going on though. I also learned after doing that for 6 mo or so, that i had to let my boy fight his own battles... can't fight them FOR him or he won't know how to do it. So i would say model the behavior so he gets an idea what to do, and then try and back off and let him do his thing later. I went from my son crying, being pushed and shoved, things taken away constantly; to one day being so PROUD (funny to say) when he actually held on to a toy another was trying to take away and said "NO!" (i smiled and thought to myself, STAND UP FOR YOURSELF!)
of course. now he's in the swatting stage.
; )