Seems to be a lot of "beer snobs" out there lately that think that if you do a secondary fermentation you will automatically get low quality beer. And I disagree 100%. Of course it has to be done correctly and I think that many people fail in that regard....
I go to secondary as soon as the head crashes on primary. That way the beer will still be giving off some CO2 and that CO2 will displace any oxygen that is present in the very small headspace that is in the secondary carboy. While transferring I also make sure that the end of the siphon hose is down into the beer as it fills the secondary so I am not introducing oxygen into the beer as I siphon. Also if the beer is still gassing off some CO2 then any oxygen that might get into the beer would get carried away by the CO2 as it leaves the beer. And finally, at that point in time, if the beer has not actually finished fermenting completely any oxygen will get eaten up by the millions of yeast cells that are still working in the beer.
In general, I go to secondary at the three day point in time but that will vary on the conditions present. My rule is to do it once the head has crashed on primary and also when the bubbles in the S-shaped fermentation lock reach one per minute or so. Those two things usually coincide quite well.
I have one large 7.5 gallon carboy that I use for primary and two 5 gallon carboys that I use for secondary. That works quite well because that way I can always have ten gallons of beer in various stages. Once in secondary there is no rush to get the beer into the keg either. Last year I waited three months before finally priming some beer in a keg for my birthday poker party. And it came out great, even with the temps getting pretty warm at times in my apartment (up to 80 degrees by the end of the day sometimes). I primed that keg with malt extract, threw it in my friend's basement (where it is cooler) and then we consumed it all in basically one evening and it was delicious.
I get very good and clear beer using this method and the beer does not suffer from oxidation at all. Yet there are people who will still try to convince me that there has to be something wrong with the beer, but they never have any evidence to back up their claims. I am very happy with the results and pretty much everyone who tastes what I brew says that it is very good beer. So I am quite confident in the process.
Haters going to hate.... We should have an actual discussion instead of this beer snobbery nonsense that seems to be going on. On a recent trip to a local brewery I was very unimpressed with what they were serving. It wasn't bad but I can make better beer than that. A friend of mine did indeed use the term "beer snobs" and I agreed with that assessment. I brew beer that anyone can enjoy. And I will stand behind any beer that I brew and even put it up against what anyone else brews.