DNS changes can take a couple of days to propagate, so be patient ... Usually it is quite a bit quicker though.
From what I have read you have started out well in that you are concentrating on domains around a subject that you are interested in ( and know something about ), this will make it easier for you to get the most from them.
Have to agree that your best thing is to read through this site as much as possible and learn from the people here.
One thing I would suggest as you are just starting out is keep really good accounting records, so keep notes on how much you spend on each domain ( including hosting and anything else you spend on them ), also keep a rough log of how much time you are spending on finding / developing / advertising.
Even if you are going to just do it for a bit of fun it is a good idea to treat it as a business .... I think quite a few people would be shocked at how much they actually spend
Most of all .. Have fun !!
Wishing you all the best.
Richard