The Windows schedule or Windows Timeline is one of the most anticipated features in Windows 10 April 2018 update. OR Microsoft has announced this feature for quite some time, but made it official this year.
Windows Timeline should (normally) work normally after the new system is installed, but unfortunately it does not happen to everyone. 
It seems that although the Timeline appears in the UI it does not save your activity. Here are some details that you should check if your Timeline does not work.
Note that the Timeline takes at least one day to gather your activity. So to see some activity you have to spend at least 24 hours from the update.
Check if Timeline is enabled
Make sure the new feature is enabled, ie you should also allow the collection of your activity history. Open the Settings app and in the privacy settings select the Activity History tab.
Make sure that I select "Allow Windows to collect my activities from this computer".
Clear activity history
You may need to clear your business history. Open the Settings app, and from the Privacy tab, select the Activity History tab again. 
In the Clearing Activity History section, click the Clear button. You can do this even if Windows 10 did not have time to collect your activities.
Temporarily switch to a local one account
This solution may be a little annoying but it seems to work. Open the "Settings" application and from "Account Settings" go to "Information". Click "Sign in to a local account" (not a Microsoft account) and you will see that the Timeline will work just fine on your local account.
You may need to stay in your local account for a while before switching to a Microsoft account. Many users report that switching to the local account will fix the Timelines that are not working, however you should use your computer for a while with a local account.
Να αναφέρουμε ότι όλες οι παραπάνω κομπογιαννίτικες λύσεις δεν θα χρειαζόταν αν η Microsoft έκανε σωστά τη δουλειά της. Οι παραπάνω λύσεις προέρχονται από το reddit και από forums όπου πάρα πολλοί χρήστες των Windows προσπαθούν να διορθώσουν το σύστημά τους μετά την last update.
- Windows 10 April 2018 Update Repair of 0xc1900101
- Windows 10 April 2018 Update BSOD all you need to know
- Windows 10 April 2018 Update how to delay the upgrade
- Windows 10 April 2018 Update expected problems in beta editions
