It depends on the dealer as it varies from city to city and you have to ensure that bookings are open in your place. You can follow the site for know about the dealers in your city: http://www.cardekho.com/Maruti/cardealers
Maruti has announced offers on Wagon R, Alto 800 and K10, but there are no announcements about offers on Ertiga. But, you can expect to get some offers later in the month. For exclusive offers, please visit your nearest Maruti dealer to find out the details.