Upgrades are automatic the instant we receive payment. Delays occur if you send an eCheque by PayPal.
PayPal will send an eCheque instead of an Instant Payment if you have a bank account associated with your PayPal account rather than a credit / debit card.
PayPal takes time to process an eCheque before they send us payment, they will always give you an estimated date in their payment notification emails.