Controlling counter for sequencer

I'm making a sequencer and am having trouble with some basic functionality. Basically what I want to do is have a subdiv~ outputting 0-3 and to trigger a counter that stays in phase regardless of changing the length of the sequence (not strictly meaning phase but I want both integers to start at 0 together). To do this I reasoned that on the last count (3) you could send counter 0 into it's 3rd inlet to set it on next trigger and send the new length. But I can't get this to work for the life of me.

Please help me!

Thanks.