I found this script to be the most effective for creating MySites in advance for all users.

#---------------------------------------------------------------------------------#The sample scripts are not supported under any Microsoft standard support#program or service. The sample scripts are provided AS IS without warranty#of any kind. Microsoft further disclaims all implied warranties including,#without limitation, any implied warranties of merchantability or of fitness for#a particular purpose. The entire risk arising out of the use or performance of#the sample scripts and documentation remains with you. In no event shall#Microsoft, its authors, or anyone else involved in the creation, production, or#delivery of the scripts be liable for any damages whatsoever (including,#without limitation, damages for loss of business profits, business interruption,#loss of business information, or other pecuniary loss) arising out of the use#of or inability to use the sample scripts or documentation, even if Microsoft#has been advised of the possibility of such damages#---------------------------------------------------------------------------------Function New-OSCPersonlSite{<# .SYNOPSIS New-OSCPersonlSite is an advanced function which can be used to create personal site for each user in a SharePoint site. .DESCRIPTION New-OSCPersonlSite is an advanced function which can be used to create personal site for each user in a SharePoint site. .PARAMETER SiteUrl The specified site URL. .EXAMPLE C:\PS> New-OSCPersonlSite -SiteURL "http://sp2010:8888/sites/TopSite2"This command shows how to create personal site for each user in site "http://sp2010:8888/sites/TopSite2".#> [CmdletBinding()] Param ( [Parameter(Mandatory = $True,Position=0)] [String]$SiteURL ) #Add "Microsoft.SharePoint.PowerShell" Snapin if ((Get-PSSnapin "Microsoft.SharePoint.PowerShell" -ErrorAction SilentlyContinue) -eq $null) { Add-PSSnapin "Microsoft.SharePoint.PowerShell" } #Load "Microsoft.Office.Server" Assembly [Reflection.Assembly]::LoadWithPartialName("Microsoft.Office.Server") | Out-Null #Get SharePoint site $Site = Get-SPSite -Identity $SiteURL #Get service context $context = Get-SPServiceContext -Site $site $upm = New-Object Microsoft.Office.Server.UserProfiles.UserProfileManager($context) $AllProfiles = $upm.GetEnumerator() #Create personal site for each user foreach($profile in $AllProfiles) { $AccountName = $profile[[Microsoft.Office.Server.UserProfiles.PropertyConstants]::AccountName].Value Try { if($profile.PersonalSite -eq $Null) { write-host "Creating personel site for $AccountName" $profile.CreatePersonalSite() write-host "Personal Site Admin has assigned" } else { Write-Warning "$AccountName already has personel site" } } Catch { Write-Error "Failed to create personal site for '$AccountName'" } } $Site.Dispose();}New-OSCPersonlSite -SiteURL "http://intranet/mysites/profile"

Source: http://gallery.technet.microsoft.com/office/Pre-Provision-SharePoint-ec781ee9