Can't help you with timing a gold purchase... or any timing wotsoever. My timing has far too often resulted in buying high and eventually writing off on my tax return. However, perhaps my strategy may be useful to you too.
I considered purchases in: commodities (DJP, PCRIX, DBC), energy (VGENX), gold and individual stocks on and off for a month or so. They weren't in my Asset Allocation, but my AA is less than 6 months old, so I reckon I could've made a 5-10% modification without really cheating. I looked at lots and lots of graphs, read lots of forum threads, but finally remembered my bad timing and decided they would all have to fit in my "self-funded speculation allocation" (initial ~$5k in 2008 mad money + profits), from which I can buy anything I want... unfortunately this is currently 100% in a barely break even Citigroup. I think this pretty much limits portfolio damage. If my judgement (or luck) improves, I get to spin the speculative wheel again. If my timing doesn't improve, I think I will end up shouting myself some more mad money (rationalization - I LBMM and don't buy lots of shoes or clothes).