Maintenance Page redirect

Borrowing from the listed exampled, it might look something like this:

when HTTP_REQUEST {
    set mainttime "10:00pm Eastern"
    if { not ( [HTTP::cookie exists "maintbanner"] ) } {
        HTTP::respond 200 content "Maintenance AlertThis site will be going down for maintenance at $mainttime. Please complete your session and logoff before then." "Content-Type" "text/html" "Set-Cookie" "maintbanner=1"
    } 
}

I'm setting a cookie in the maintenance splash page, so that after the refresh it'll bypass this for the rest of the session.