Absent a change in plans, the nomination will come early next week.
One senior administration official told multiple people late last week that the nomination would not come this week. There is no sense of a hastening of the pace that you would expect if the announcement were going to be tomorrow.
In addition, the President has scheduled a trip to Buffalo next Thursday, with a focus on economic issues.
As a practical matter, that leaves a window of Monday to Wednesday for the announcement. My general sense from the public and private comments of the Administration is that earlier in that window — Monday or Tuesday — is more likely.