Both George and Fiona agreed that they weren't ready back in S1 - that was when she told him about Robbie and basically the hurt he had caused her. It made sense for him to go to Katie at the point he did since had been spending time together, etc.
In regards to your question, I don't necessarily think it was too soon, it honestly depends on the person. The reason I don't think he told Fiona at that point was because they both wanted fun and not serious at the time, etc. (that of course changed when Jan's bombshell hit). That being said when he told Siouxsie it seemed to come out of nowhere, but as Erik said in one of the interviews that kind of thing can come when you least expect it.
Facebook and Twitter were the spots to go to while it was airing. It was interesting to see the reaction of those in NZ after it had already aired in Australia, because you were just waiting for those who weren't spoiled to be hit with the bombshells that were dropping, etc.