There's no timing issue here – UEM only gets to run after Windows has created the local user profile folder.
The only potential issue I see with this approach is if you're using this in a persistent environment where you do not remove the profile at logoff. In that case it might happen that user abc logs on but folder C:\Users\sgr still exists on disk, causing the condition to match...
Using the environment variable condition to check %username% does not have that (potential) issue.