If the choke is really working correctly and the carburetor is properly installed (it's on a 2bbl intake, right? Or did the kid put one of those dumb "adaptors" in place between the 2bbl carb and the 1bbl intake?), then this problem is often down to the carburetor and fuel line are emptying out overnight. You then have to crank the engine until fuel is lifted from the tank into the lines and fills up the carb. That's a lot of cranking! This can be caused by a number of different problems: leaky fuel pump valves (replace fuel pump), and/or an air leak anywhere in the fuel line are two prime suspects. Either or both problem could be aggravated by heat soak causing the carburetor to boil dry after engine shutdown.

The first thing to do is to check for an empty carb before the next time you try to start it from cold: Have the engine off and the choke open, remove the air cleaner lid, and peer down into the carb while you operate the throttle linkage half a dozen times. You should see a strong, solid shot of fuel each time you operate the throttle. If no shot or only a piddly weak one, the carburetor's empty or nearly so and you need to hunt down the problems as described above.

If you do get a healthy shot of fuel indicating the carb's not empty, then it gets tougher; the problem is then likely ignition-related and will take some more involved troubleshooting.