Getting to school on time with an older child? Warn them that if they don't stop, I'll be taking a set amount of TV/DS/computer time off them after school. Or whatever else they love doing. When they protest, I calmly double the time. 5 minutes less, ten minutes less... And if they have earned the sanction, it happens.
Do you have to use time out as your only way of discipline? I always found it worked best if I didn't overuse any one method. For the situation you mentioned, I would probably limit myself to The Voice and only step up to confiscations etc if the behaviour was then repeated. My parents punished rarely- gave their punishments enormous punch .
How about having a specific activity for when she's ready for school which is something interesting enough to prevent her being bored while she is waiting? If you explain the problem to her, she might have some ideas of her own.