I am a firm believer in the fact that as a Parkinson's patient YOU must manage your meds daily in regards to how you are responding to them as opposed to the usual run of the mill take this 3 times a day or every 4-6 hours, etc. You cannot manage Parkinson's like that. If you are going to get anywhere with the meds this is imperative.
Since diagnosis I have never followed a doctors orders as to how to take levodopa. Some said every four hours or three times a day or whatever they thought. If you are on levodopa and you are stiff or off, you are not getting enough. If you are dyskinetic and you are taking an agonist such as neupro, requip or mirapex, you have too much. You need to cut the levodopa back to compensate for the agonist.
I have had PD for 16 years now. I am on levodopa/carbidopa only, the TEVA generic at that! NO other meds. I am able to be on for most of the day with little off time. Yes its still difficult to walk and do things but I take care of a home, 2 dogs, take out the trash, go to the store, etc.
Here is what I suggest: start out in the morning and take 1 sinemet, levodopa or what ever you are on. see if this results in an "on" state. If it does note how long before you FEEL like it is getting difficult to move around. If it does not the next morning increase the first dose by 1/2 a tablet and then again see if this gets you to an "on" state. Then wait to see how long it lasts.
This is your "window".
In my case I take 1 1/2 levodopa first thing before I get out of bed. then 1 hour from that time I take 1 1/2 tabs every hour for the rest of the day. I am able to functon well all through the day. I have read many posts about dyskinesia and some people who are on a dosage of 3 or 4x a day and they're still "not responding". Hope this helps somebody.

Jim, do I have it figured right that you're taking around 2000 mg. per day of Sinemet? And you're not having major problems with dyskinesia? Even if just one person can do that, it's still good news.

Is there an approximate dosage of ldopa when dysks start.

I am trying to keep below 800 mg per day and I do not suffer badly from them.

Neil.

everyone is different, i too try to stay under 800mg but go up to 900 at times.
i take combo of immediate release and controlled release sinemet, the 50/200 pill but count it as only 120mg in my calculations since assume 60% bioavailable. i'm cheating

only taking sinemet until recently,
i have added azilect which doesn't seem to make much difference, stopped it awhile back after a 3 week trial but decided to start it up again since wearing off is happening quicker. tried neupro patch samples up to 2mg, didn't notice any side affects or benefits but stopped since i can't rely on samples and can't afford the patch which would cost at least $450/month. if i could get it in canada it would be $250, checked with 2 canadians, it would sure be nice to just slap on a patch once a day and pop a few SINEMET CR's and not have to worry about missing a pill or protein interference which really decreases my l-dopa absorption.

i would have to assume a quick acting inhaled l-dopa would reduce the dyskinesias since you'd be able to take a lesser amount of oral l-dopa daily since you wouldn't have to be 100% ON all the time, you could use the inhaled l-dopa to "TOP OFF" assuming you could afford it. might be totally off base in that assumption.

have had dyskinesias only once, had to go to a party, IR sinemet wasn't kicking in, had taken a CR but didn't realize it was about to kick in, so took 100mg, that kicked in and then at the party the CR kicked in, that resulted in more mild swaying/bobbing than a lot of jerky motions.

I've read that 1200 might be considered high.

Starting about 6:00 AM and every two hrs until 10:00 PM I take one standard plus one cr or about 250 mg total. That adds up to about 2000 per day. Occasional dk (once month avg) but with cause (i.e. extra meds). Three years now and have reduced overall.