Before you get into timing, what is the history of the motor? Was it put into storage with gas still in it? Did you try some starting fluid? It's a whole lot easier to give it a shot of fluid and see if it fires, than taking things apart to verify timing. With a motor that new, if it's got spark and compression then most likely the problem is a clogged up carburetor.
That said; to check mechanical timing, to be sure the flywheel didn't shear the key and slip. Pop the valve cover and look at the cam while you turn the flywheel to TDC. Every other revolution the valves should both be closed when the TDC mark on the flywheel lines up with the indicator. This will help:
TOHATSU MFS 4 Manual Online: inspection of idle engine speed, Inspection Of Ignition Timing. 1. Start Engine And Run For 5 Minutes To Warm Up. Attach Tachometer To Spark Plug High Tension Cord 1 To 2. Check Idle Speed. More Accurate And Stable Reading Can Be Obtained When Tachometer...
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But like I said above, try the starting fluid first. If it runs for a moment with starting fluid, then the timing is fine.