Once you know it is working, then you can send them in and receive credits for ones you sent earlier. I would always recommend that you wait until getting credit before sending more - so that you at least know if you are doing it correctly.

You will remain way behind, and not really sure how many they have received, etc., but you can get into a cycle where you should get credits regularly if you mail them in regularly. This only works if you continually write them and send them in. I meant it was 2 weeks from the previous time credited. When I said they credit them about every 2 weeks, I didn't mean it was 2 weeks from the time you mail them in. I'd say a more realistic time would be more than 6 weeks. Three weeks is actually a short time from when you send them in. Mostly that I wasted 100 postcards/postage and more importantly a couple days of my time. I've been waiting far longer than 3 weeks so I'm not sure what to think.