Flight connection to Shanghai from Beijing

I arrive into Beijing on a BA flight from London and my plan is to fly to Shanghai as soon as I can. I'm guessing as I'll book the Beijing-Shanghai flight with a different airline, I will have to pick up my bag and recheck it in? Assuming I'll have to pick up my bag and check into the domestic my flight to Shaghai how long should I leave between the 2 flights and what time should I book my flight to Shanghai for?