Price of bitcoins has gone down a bit in compare to last few days so I think this is the best time to buy bitcoin and hold till the end of the year as price will surely go above $5000 at that time and that would be the best time to sell bitcoins.
Yeah bitcoin and some altcoins are on sale as of the moment so its best to buy now but make it sure to have more money to buy when there will be more dip in coming days.