I've always done a physical check on timing marks. Making sure they are lined up by rotating the crankshaft and stopping at the crank timing mark. Then I would look at the camshaft gear timing marks and see how they line up. I would do this three or four times to make sure all the marks continuously line up. If you are off one tooth on the camshaft, you should be able to see it in the marks not lining up exactly.

You may be able to rough check the timing with a compression test as well provided you know the necessary info such as what normal compression for that engine. Say if the normal compression is 150psi and all cylinders are showing 85 psi in a wet condition (oil injected through spark plug hole) then there is a chance the timing is off. The reason I say this is because air may be leaking through an intake or exhaust valve because they are opening or closing late. Say for example on the intake side if the intake valve is still opened while the piston is climbing up the cylinder on its compression stroke, some of the compressed air will escape back through the intake causing a low compression reading. I think you may now see where this is going to possibly indicate the problem. Remember that all cylinders need to show the same low compression readings. If only one or two shows the problem, you have a compression problem maybe in stuck valves or something else. Remember that late or early valve timing will be the same in all cylinders provided they are all relying on the same camshaft. In a DOHC engine one cam handles the intake while the other handles the exhaust.