I do not recommend delaying your passage through immigration by an hour as your bag may be gone from the carousel. BKK has excellent bag delivery time. I flew in this week on AC and my bag was delivered 20 minutes after I disembarked at the Satellite terminal. That's an excellent delivery time. BKK usually collects bags from the last bag notice to ensure that the carousel is empty for the next flight using it. If you wait an hour and are delayed at immigration (non priority pax can take 30-60 minutes to clear, I cleared in 10 minutes using the priority line.) it is probable your bag will be gone and sent to holding.
I recommend that you clear immigration, and collect your bag and then go meet your friend at their flight's baggage carousel. The arrivals hall is large with seats next to each carousel. It is less hectic than waiting outside the baggage delivery zone. There are electronic displays giving every flight's baggage carousel.