If you are new to silkies, I would recomend that you wait until you see an actual fault that you want to get rid of, like the most obvious at hatch, missing or extra toes, completely lacking any feathering on the middle toe. As far as the crest size, things like vaulted skulls are a matter of personal preference. If any develop cross beaks, cull them. Split wings can be seen fairly early. I wouldn't go heavy handed at hatching time, as some wing joints take a little time to get strong. Low wingset, if it is a warm day, can be deceiving. They may just be trying to cool off. I have had some really gangly, awkward chicks and started birds turn out to look REALLY PRETTY later on. Comb and wattle color and type and size you won't know until they reach sexual maturity pretty much. Some of my young birds had very nice crests, then time in the flock and breeding has taken its toll on their girlish good looks. Their crests are sometimes short and uneven later in the breeding season.
Just saying, you need to grow some out, even some ugly ones just to pay your dues and see how your lines of birds mature. Some you can tell a lot early, some change a LOT, for better and for worse.