Yes, give yourself an hour if taking the bus. When trying to make an ADR, I'd take a car over the bus any day . We ate there last Wednesday and were horribly late for ours thanks to bus system (and we gave ourselves plenty of time). At check in they were nice about it though. We were celebrating dd's 4th bday and asked to sit in the Ice Cave and were given awesome round booth just under the embedded T-Rex skeleton. I think it was the best seat in the house! This was a favorite on our trip. Atmosphere, food, and service were great. (The chocolate extinction is super yummy). So worth the headache getting there.
PS- our ADR was for 5:15. We arrived closer to 5:40ish. Upon arrival it was busy, but was able to walk right up to podium. By the time we left, 7:00???, it was a total madhouse out front. Crazy giant line to check in.