Maybe you can change the approach to solve the problem and use Azure Data Factory to configure an Azure Batch Job that will start the sync at the time you configure it using an Azure Az script like the one shown below:
$resourceGroupName = "<resourceGroupName>"
$serverName = "<serverName>"
$databaseName = "<databaseName>"
$syncGroupName = "MySyncGroup"
Start-AzSqlSyncGroupSync -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName -SyncGroupName $syncGroupName