Hi,

       There can be an initial scan but it is not just an initial scan. There are two options:

1st option: If the Default Administrator scan is still set and not disabled and the install is a fresh install or even an upgrade from SAV (should) do an initial scan like the default admin scan at time of install.

1.1 Go to Clients, Policies.
1.2 Click on Antivirus and Antispyware policy.
1.3 In Antivirus and Antispyware policy click on Administrator-defined scans.
1.4 If the Administrator On-demand scan then you will get a scan running.

2nd option: Set a scheduled scan in a 'temp' group. Clients install to the temp group and get the scheduled scan, then clients can be moved out of temp group into their normal group which would not have a scheduled scan.

Also try the following :

Open the SEPM console
Go to the Policies page, or select the appropriate group in the Clients page and select the Policies tab there
Edit the desired Antivirus and Antispyware policy
Select and modify Administrator-defined scans in the policy editor.
Click OK to save changes, and ensure the policy is applied to the correct client groups.