Hi, kind of a tough question to answer as it depends on what you are interested in buying. Certain items are available for the whole expo but others sell out quickly. If it's an inaugural race, I would plan on 3 hours before the expo "officially" opens on the first day. For example, for Avengers expo last week, I was in line at 7 am PST (expo opened at 10 am) and there was already at least 50-75 people in line. Disney let us in to the expo about
9:15-9:30 am so that helped decrease wait time. Some merchandise was already sold out by noon but the Dooney & Bourke purses (separate line) lasted for both days except for the satchel style.
Disneyland is kind of unique since so many local people come to the expo to buy merchandise to resell on ebay-I don't think that is as common in FL.
It also depends on how many items Disney lets you pre order - typically pins, necklaces, ear hats. Lately we can pre order jackets (which always sell out quickly) and D&B purses (except for Avengers).
Mugs and wine glasses usually sell out very fast (those items weren't offered for Avengers - just beer glass and water bottles).
Anyway, not sure if that helped but happy to answer any other questions. I've been doing races since 2010--I ALWAYS go get the merchandise first then go pick up bib etc.
