Despite your knowledge on trading, have you been applying techniques of testing on better coins to trade in at that particular point in time? You may endeavor using the coin market cap, this avail you that opportunity to check where the particular coin is been ranked. Is it among the first 20? And stuff like that. You can also confirm at exchanges their value at that period in time. This however still considerend depend on the type of exchange.
You apply to yourself what you know but you need to have the knowledge, and you will think of ways you can do it right so you can do it without losing.