Hi! What can I do while waiting for my flight in BCIA?Am arriving 6am and flying 8pm, with a valid Chinese visa

As you have a valid Chinese visa, you can go out of the airport. I suggest you have a short sightseeing in the city to Tiananmen Square and Forbidden City. Then you can wander around at Wangfujing Pedestrian. After that, go back to the airport to catch your plane.

Is there a place to sleep/shower in the airport or nearby? A place to leave luggage?

Many thanks for ur help

You can find hourly lounges inside at T1, T2 and T3. There you can have a rest and in the VIP rooms, you can have a shower. Or as I know, you can find an area at Arrival Hall to have a shower as well. As for this, go and consult the airport staff about the exact information.

There are luggage-left counters. At T3-C, you can find that at East and West of public space of Arrival Hall at 2nd foor.

Many, many thanks Bella from Finland. More power