The end of the month is an arbitrary date we set up in our minds. Day to day, week to week, month to month, full moon to full moon, year to year, whatever.
Sell 'em when it fits your plan not when it fits the calendar.
As long as your long term average is positive, it's all good.
January is done, good or bad (your case very good), let's fight for that February, and learn and earn.
These thoughts are just mine, not right, not wrong, just thoughts. Invest in what you believe in, not what I believe in. Do your research, and invest in the facts.