A freshly saved (or updated) DWG drawing, RVT project or IPT/IAM model may not appear immediately in the Autodesk 360 cloud. CAD files are not saved to the cloud directly (it would slow you down). A file for web-cloud is first saved locally to a synchronized hidden folder (cache) - by default to C:\Users\USERNAME\AppData\Local\Autodesk\Autodesk Sync\Cloud\YORCLOUDLOGIN\.
Then the Autodesk Sync service cares about automatic transfer from this folder to the Autodesk 360 cloud. It can take a while, so your drawing appears in the cloud only after a minute or two. If you close AutoCAD (Inventor, Revit...) and immediately switch off (resp. hibernate or disconnect) your computer, the drawing will be synchronized to the cloud only after the next start of the system. Possible collisions (new version, broken upload, etc.) are resolved automatically by Autodesk Sync.
So a simple rule applies - do not immediately switch-off your PC if you need your drawing updated in the cloud just after saving it. The cache folder is synchronized with the cloud every minute (60 seconds), plus you need some time to perform upload of the very DWG file (or project/model) - depending on its size and on your internet connection speed. So it is safe to wait a couple of minutes.
There is also some delay when the cloud generates the documents thumbnail (preview) but this delay doesn't restrain accessing the cloud file from your mobile AutoCAD 360 or from other cloud application.