Hi George,
First, I agree with those who have advised not to let yourself go "off" before you take your next dose of sinemet, it is much harder to get on again.
However, no-one has mentioned breakfast. It is very important to take your first meds in the morning before you have breakfast. Then they last a lot longer. I don't have breakfast until after I have switched on (20 to 30 minutes). Similarly, try to adjust your other doses between meals, and not too soon after a meal.
Best wishes
Ron