When your payment is cleared, dealer usually gives you a provisional PBO the same day, which has neither any booking No. nor tentative delivery date mentioned on it.
You should ask for the confirmed PBO after 6-8 working days of the issuance of provisional PBO, which mentions both the booking No. and tentative delivery date.
I also followed the same procedure while booking Alto VXL AGS (Tentative delivery month: October).
Hope this suffices your concern.