I'm using the 5 by 5 stronglift program just for the dummbels. I know it's not ideal consdiering that program is used for an overall body workout. But because I want some muscle on my arms I do 5 lifts by 5 reps. And I started with 5 pounds (funny I'm in Australia and use KG but the weights are in pounds). So thats around 2.5 kilos. Then the point is to try and up the weight everytime you go into a session. Though since I hadnt used weights on my arms I didnt up the weight every session, I did it every week that way to make sure I would gain muscle. Orignally I tried the 10 pounds but I wasnt able to do it. Now, I'm up to 12.5 pounds..... lol so im sorta still practising that.
The point is, with the strong lifts program you keep upping the weight forcing the muscle to... I guess... GROW. I thought orignally that I have put on a bit of muscle, but now i'm not too sure. You know how those things go when you loose weight/add muscle "Was that there before? Oh Damn I can't remember".
Anyways, good luck with the dummbells, and if you choose to go by stronglifts, I suggest you research it in google. You only up the wegiht by say 1 kilo or 2.5 pounds each time.