Late Bird challenge requires you to start your run whenever frontrunners would reach ladder 11.
This challenge originates from the times when the condition for awarding [FAUTO] modifier to the ladder was for the top ladder to be as far as default_AH_ladder from the subject ladder.
Challenges are usually played in [DEF] rounds and since default_AH_ladder equals 10 for them, L1 would receive it's [FAUTO] when the top would become L11.
Winning is very possible although requires you to be very active and travel through ladders as fast as possible. 10-ladder gap is quite a big distance to cover by itself, not to mention ladders getting walled pretty often.