The best time is if you have the capital investment, you know the basic, the do's / don't and that's all about it. You're on your way of becoming well seasoned trader.
depend on the type of trade the op is talking about. Buy a particular coin such as bitcoin, you we need to study price action. You should always buy at a lowest price possible and sell at a highest price possible.
Yes, since you are new here and it is good that you got the basics right but you know what is the biggest problem is ? It is actually finding the cheapest price of coin and then the maximum price. Sometimes even the owners cannot determine the pump and dump of a coin against some big investors.