Powershell – Need to add a “Wait” command to a Powershell script

Here is my current code:

Write-output “ENTER THE FOLLOWING DETAILS - When Creating Multiple New Accounts Go to           EMC hit F5(refresh) and make sure previous new account is listed before proceeding to the       next one”
$DName = Read-Host “User Diplay Name(New User)"
$RUser = Read-Host "Replicate User(Database Grab)"
$RData = ((Get-Mailbox -Identity $RUser).Database).DistinguishedName
$REmailInput = Read-Host “Requester's Name(Notification Email goes to this Person)"
$REmail = ((Get-Mailbox -Identity "$REmailInput").PrimarySmtpAddress).ToString()

Enable-Mailbox -Identity "$DName" -Database "$RData" 
Set-CASMailbox -Identity "$DName" -ActiveSyncEnabled $false -ImapEnabled $false -    PopEnabled $false


Send-MailMessage -From "John Doe <John.Doe@xyz.com>" -To $REmail -Subject       "$DName's email account" -Body "$DName's email account has been setup.`n`n`nJohn Doe`nXYZ`nSystems Administrator`nOffice: 123.456.7890`nJohn.Doe@xyz.com" -SmtpServer exchange@xyz.com

This code works flawlessly about half the time, but the other half I get this error in return:

ENTER THE FOLLOWING DETAILS - When Creating Multiple New Accounts Go to EMC hit
F5(refresh) and make sure previous new account is listed before proceeding to
the next one
User Diplay Name(New User): Jane Doe
Replicate User(Database Grab): Julie Doe
Requester's Name(Notification Email goes to this Person): Joanna Doe

Name                      Alias                ServerName       ProhibitSendQuo
                                                            ta
----                      -----                ----------       ---------------
Jane Doe                  JDDAFA               exchange@xyz.com      unlimited
Set-CASMailbox : Jane Doe is not a mailbox user.
At C:\emailclientbasic.ps1:11 char:15
+ Set-CASMailbox <<<<  -Identity "$DName" -ActiveSyncEnabled $false -ImapEnable
d $false -PopEnabled $false
+ CategoryInfo          : NotSpecified: (0:Int32) [Set-CASMailbox], Manage
mentObjectNotFoundException
+ FullyQualifiedErrorId : 292DF1AC,Microsoft.Exchange.Management.Recipient
Tasks.SetCASMailbox

So if anyone could help me throw in some kind of wait command after the mailbox is created and wait until the user's mailbox is created before the script disables ActiveSync, etc it would be really helpful. I believe that simply using the -wait switch does not work.