The way this glitch is triggered is by starting driving school or bike school after the blackboard has been created. It you are extremely unlucky and your blackboard just happens to be in the same slot that was used by a cone from a previous lesson then the school will delete it.
I can't think of anything you can do to avoid this glitch. Your best bet would be to test for it immediately after the blackboard is created. You could also gold out both driving and bike schools before completing the Wang missions, but then the glitch might be lurking.
The thing is though, there are 10s of thousands of object slots, and only a dozen or so glitchy cone slots, so the chances that this glitch will occur are pretty slim. We've seen a couple of cases recently, but before that I've only come across maybe 4 other incidents. And I would think that a lot of players would complete bike school after Wang missions, or may repeat lessons for gold later in the game, so I would expect that players are triggering this glitch all the time, yet we've seen very few problems over many, many years.
Glitch Avoidance Tips for a New Save:
Start your new game without loading a previous save or you'll be missing the rapidly respawning extinguishers in the fast food joints and sniper on the hill above the SF airport. Or if you want, you can carry over the busted/wasted bonuses from girlfriends. But Katie and Barbara can be met anytime anyway so you still have options.
Avoid saving at Madd Dogg's mansion or your basketballs will probably disappear forever. This is easy to fix on SnP, which will even move the disk so it's safe to save at the mansion, but console players will probably want to avoid this save location. Old glitch, almost everyone knows this one.
Avoid exceeding the daily workout limit on gym equipment or after an (invisible) in-game calendar year you might run into the gym glitch that prevents CJ from working out. If you want to workout a lot in one day, exiting and entering again will reset the workout stats.
Avoid using the pedestrian riot button cheat associated with golf clubs. This cheat will trigger the game breaking Madd Dogg glitch, and cause major problems with other missions as well.
Make sure that driving or bike school doesn't delete your blackboard before moving on from the Wang missions.
Don't get too clever and try to collect the rare mafia car from the debt collectors until after the Are You Going to SF mission is available or you'll kill the Badlands mission strand. (Related: Don't edit the cities unlocked stat while still in the early LS mission strand or you'll kill the LS phone call thread.)
Hmm... I feel like I'm missing something obvious, but what?