That's not very indicative that you have a leak. It takes time for CO2 to build up in your tubing before its pushed through your automizer (hence why upping your outflow starts it quicker). Once the pressure is built up then everything flows fine, just like you've observed. Just up the working pressure of your regulator and see if it starts up quicker in the mornings. If you have a regulator that has a preset pressure then you can just start the CO2 an hour early so by the time you originally would like the CO2 to turn on - the pressure is built up and everything flows properly. If none of the above works, spray everything with soapy water in a spray bottle (mainly around the check valve since you think that's the problem area) and look for bubbles. I really doubt you have a leak since your automizer is working - it's just build up time!