I have Lumia 820 from a month and I didn't get even a single push notifications from Facebook and Twitter.Now I'm facing the issue with Whatsapp. I had reset my phone once but no use.Hope Microsoft solves the problem.
In all your email settings, set Download new content to as item arrives. This will affect other apps with push notifications to receive them in real time. This has been an issue since wp7 but this is a neat trick if you want real time push notifications across all your apps.
whatsapp is working just fine, 620 and 920. Chile.I have the same problem on my lumia 620 with WhatsApp. Notifications come through late. I?m using the last firm. Brazil here.