Let's say you're a slow starter who's fighting a fast starter. What do you need to do to survive the fast starter's early onslaught?
I say good defensive footwork and head movement, while staying as calm and relaxed as possible to avoid getting tired. Let him swing away, tire out and frustrate him. But nail him with a few hard shots to get his respect early. Don't want to run too much and make him overconfident. That's usually my MO. I'm sure some others will have other good suggestions.
I'm a slow starter even in sparring. It takes me a round or two to get into things. Problem is that I've too many fights starting slow. I always finish strong and would love a few more rounds, but that's amateur boxing.