Andrew, I'm not sure I understand the issue.  Currently you send a reminder after a due date, but now you want to send it before?  Or you want to send it at the exact date/time something is due?

If the former, you can adjust your calculations to trigger the workflow to send it before the due date.

If the latter, I would build a notification workflow on the list itself.  Use the site workflow to find the items that are due that day, and have it start the notification workflow on the list item itself.  Then in that workflow you can have a Pause Until, that waits until the exact time that day to send the notification.

Thanks, I'll have a go.

Currently I've done the following which seems to be working:

Site workflow below scheduled to run only once each day so far. May well have to up this to at least twice a day.

The Call Web service, starts a list workflow:

Looks good.  Couple of questions.  1) Why would you need to run the site workflow more than once a day?  If you're query is looking for everything due that day, there should be no need to run it more than once. 2) Why do you have a "Run If" in your list workflow?  Again, if you're query in the site workflow is only finding items due that day and that are Active, it should only be starting the workflow for items that are due that day. 

What you may need in your list workflow, is a Run If before the notification is sent that double checks the task hasn't been completed.  If that's what you were trying to do, the Run If should be after the Pause, not before it. 

Brendan,

Thanks!

My thinking of running a site workflow more than once is: What about items which are added during the day and after the initial scheduled run?

Sometimes an item is added with a due date of today and due time of 18:00.  Thinking about it I could tweak one of my other item list workflows to look at the created v due date and it they are the same get it to start the new list item I've created.

Thanks for the heads up on the list 'Run if'. I'll move it. That's what exactly what I'm trying to do.

Andrew

For the same day scenario, I'd setup the workflow on the task list to handle that.  Have it run when an item is created, and the first step would be to check the due date.  If it's not the current day, then it could end.  Otherwise it would go on to the notification process.

Thanks,

Coming from InfoPath and SPD. Tasks are very alien to me for accompishing things, yet it seems Nintex workflows are all over them.

I'll have a go.

‌, if one of these responses answered your question you could you mark it as such?  Thanks.