estimated-progress.ps1

# This is just an example for time estimations in write-progress,
# though a simplified scenario
$sitesBareMinimum = Get-SPOSite -Limit All
$starttime = Get-Date 
$count = 0 # kind of an index, counter
$total = $sitesBareMinimum.Count
$sites = $sitesBareMinimum | ForEach-Object {
    $site = $_
    $estimation = ""
    $now = Get-Date
    if ($count -gt 0) { # noone wants a DividedByZeroException :) 
        $elapsed = $now - $starttime # how much time has been spent
        $average = $elapsed.TotalSeconds / $count # how many seconds per site
        $totalSecondsToGo = ($total - $count) * $average # seconds left
        $span = New-TimeSpan -Seconds $totalSecondsToGo # time left
        $estimatedCompletion = $now + $span # when it will be complete
        $estimation = $estimatedCompletion.ToString() # readable estimation
    }
    $count++ 
    $percent = 100 * $count / $total # percentage complete
    $status = "#{0:d5} of $total. Est:d $estimation. $($site.URL)" -f $count # aggregated status message
    
    Write-Progress -Activity "Getting information for " -Status $status -PercentComplete $percent
    $siteWithMoreInfo = Get-SPOSite -Identity $site.URL # the actual time consuming operation
    $siteWithMoreInfo # return the site with more information
}