The amount of time it takes to sync events varies based on if you have upgraded your SendGrid account to pull additional info.
If you have not upgraded your SendGrid account to allow for extra info such as subject line etc. Events will process almost instantly as we do not have to retrieve any additional info.
If you have upgraded your SendGrid account there will be a 5-10 min delay before we can get the extra info from SendGrid (there is slight lag here on the SendGrid side before we can access it)
We use the timestamps from the events so they will appear correctly on the users timeline when they are processed.