I mark mine at home. I use one of those plastic things to put a red or black line on my ball with a Sharpie.

I usually mark mine within the first few holes, with a brown tree scuff!

I mark all 3 balls in a sleeve when I open it on the tee box and then remark the balls as necessary when the marks start to fade from the ballwasher and use.

I mark my golf balls prior to the round I am going to play. I play NXT Tour Ball. I mark it with a line over NXT and black out the last T on Titleist,

I mark my balls before the round, and usually three at at time (I will lose one or need a provisional - ha!) I will usually have a sleeve or two in my bag, I don't mark those in advance as I have been known to donate partners a ball or two during a round

The phenomenon of marking a golf ball is what, 15 years old?! I mark my golf ball by not marking it. That way it stands out in a crowd. I found a Titleist Pro V-1 yesterday that had a Texas Longhorn logo emblazoned on it. And the guy had also marked it! What are the odds of that particular golf ball appearing in the rough on a Pacific Northwest golf course where there's another ball exactly the same?! I'd rather take my chances playing the Powerball lottery. They're better.

Ha! If you found that ball out at Bandon Dunes it probably was mine.

I also mark my Pro V1-x balls at home. Typically, I will mark the dozen and grab a sleeve or two to toss in the bag as needed. A friend showed me a tip that he used for tournaments. Instead of putting the same numbers back in each sleeve, he rotated the numbers so that each sleeve had 3 different numbers. On those RARE occasions when I need to hit a provisional ball, I know that I will be able to identify which ball is the original and which is the provisional! Oddly enough, I pay more attention to noting my marks on the ball than the actual number when I get to it.

I used to have my daughter pre mark her balls before every tournament. A few years ago at the WI PGA Junior championship, she lost a practice ball (previously used in another tournament) in the right side rough during a practice round on the 18th hole at Brown Deer (where Tiger had his first pro hole in one). The next day in competition, her group was waiting at the tee box on 18. I walked ahead and found a ball in the rough, which was hers, with the exact same marking as her new ball in play. I put it in my pocket, and sure enough, she hits her tee shot over by me. She still will pre mark, but uses different colors and will modified markings if the situation requires (playing a provisional, the marking needs to be different).

I also mark my ball before heading to the course. Like some of the other members said I don't think you are alone, also I know I've read that some tour players mark there balls before the round.

I mark a sleeve of balls up at home and then put the sleeve in my bag to use when needed.

I will mark my ProV1 after warming up on the range and right before hitting the putting green for some relaxation. That way I know I am good and ready for the day.

As long as you mark it before the round starts I think your golden. In the tournaments I've played in most guys just mark them on the 1st tee box.

Marking your ball should just be part off your pre round routine / practice. Before the tound, when you at home, whenever it feels right. Just make sure it is a Titleist.

Wish I could drill the ball like I do a molar....