Timer Beseler 23cii

I am trying to figure out exposure time but the image stays lit up after the timer expires. Not sure if it’s exactly connecting to the timer. I am new to printing and just curious where the Timer plugs into the color head power supply?

Thanks for any help!

Welcome.
Generally speaking with this sort of setup, the timer plugs into the wall power, the power supply plugs into the enlarger plug on the timer, and the enlarger light source plugs into the power output plug of the power supply.
It would be best to wait to here from those who use your specific combination of equipment, in case there are any special concerns.