Parallax will sync timesheets hourly, usually at the top of the hour but it may take at least half an hour to get through all the data in that sync session. The actual time at which a sync is going to complete is not predictable as that is determined by the timekeeping system used and the total number of projects, volume of individuals assigned to each timesheet, etc.
Parallax also will run a nightly sync (over night) that checks for time changes made earlier in that day not already recorded in Parallax. Again, the nuance of the timesheet system used and how each integration works can be different.
The hourly sync will look at projects that are In Progress, Awaiting Start and On Hold. It will not sync time to a project marked Completed.
You can do a project sync at the project level at any time but please note that Parallax will run the sync through however updates to Insight Reports may take longer due to the cycle of data that needs to update from the project level and then throughout all insight reports.