Sdrothco - great news! I always enjoy good outcomes. Not sure if I mentioned this earlier - it is best to pair tangible rewards with verbal praise, hugs, highfives, or 1:1 attention, etc. Reason being - it will make fading the reward easier and hopefully lead to the development of intrinsic motivation.
On time-outs - they are most often misused. I believe you said you were not using time-out which is good. Time-out can be very effective when used in the correct situation. It should be determined if the child is engaging in inappropriate behavior to gain attn before using a time-out. A child trying to escape a demand situation who is put in time-out is being reinforced bc he escaped demand. The time-out actually serves to strengthen the child's maladaptive response. This is different from having a kid in full throttle meltdown mode take a break to calm down - as long as he doesn't escape the demand that started the meltdown in the first place. 1,2,3 Magic does use a blanket time-out, which I do not like. I've modified the approach to match my son's escape-maintained behavior and have had great results. That aside, it's still a great book. I've modified the approach to match my son's escape-maintained behavior and have had great results.
I had this problem with the Montessori preschool. The teacher would send my son to time-out everyday bc he refused to complete seatwork. As soon as seatwork was presented he would get up and go get another preferred activity (the seatwork was not appropriate for his gt abilities but that's another story). I tried to get them to keep him I'm the classroom so he would not escape work. They refused and this just led to a whole host of issues. Basically my son learned he could get out of doing things at school by engaging in inappropriate behaviors.
With our kids we always have to be on our toes. They learn and adapt so fast. Be prepared to switch up rewards, etc as what motivates today may not tomorrow. You may see a reoccurence of unpleasant behavior. If this happens - don't give up! Assess your approach and determine if you are being consistent. If you are being consistent, your approach may not be compatible with the function or root of the behavior. If this is the case, you will need to modify your approach. Be careful with this as many times parents react to a change in behavior by abandoning their approach - which many times is a mistake.
As we say in the field - catch 'em being good and praise - it's the single most important thing we can do. So often we get caught up in life's responsibilities that we provide more attn to the child who is mis-behaving than the child behaving. I know I make this mistake as a Mom.
Wishing you continued success!