We will be heading to Venice from Florence on the morning train, and will only have 2 days there. Burano is high on my list as it looks so beautiful, does it make sense to go there from the train station before heading to Venice? Will it save us some time, and do they have any luggage storage facilities? We are backpacking so that isn't necessarily a deal breaker. Grazie!
There is a luggage storage facility inside the Venezia Santa Lucia station, so you could leave your bags there then head to Burano upon arrival. The other option is to head to your hotel first, if it's not too far away, then go to Burano after dropping your bags at the hotel. The storage office is managed by the Kibag company on behalf of the train station operator company.
https://www.kibag.it/deposito-bagagli-venezia/deposito-kipoint-venezia-santa-lucia/
Why do you want to lug your luggage on your back to tour Burano? Does not sound like fun to me? Go to your hotel and drop your bags if you can't check in, then go to Burano. You will need to to go Fondamente Nove and get the No 12 boat to Burano. Depending on your hotel location, you can walk to Fondamente Nove, or take one of the 4.1/4.2 or 5.1/5.2 boats to Fondamente Nove.
Since you will apparently doing a lot of zipping around on vaprettos, buy multi-day passes when you arrive.