I've found a save file that, with very careful play, could allow the community centre to be finished by Fall 1. The file number is 188219898. Mouseypounds' Stardew Predictor https://mouseypounds.github.io/stardew-predictor/shows the travelling cart will provide pumpkin and eggplant, which means the greenhouse could be completed as soon as corn is ripe in the summer. That by itself isn't too unusual, but this file also has walleye (which is otherwise unavailable until a rainy day in Fall), along with red cabbage, rabbit's foot, nautilus shell, truffle and tiger trout (the other Fall fish). The timing isn't perfect - lots of expensive items in Spring - but that's a fine selection of items if you're looking for early completion. The only tricky item missing is the duck feather. I'm going to give it a go and see if I can pull it off. I think money will be a key consideration, as there are no convenient mushroom levels at the right times, and I'll need to build a lot of farm buildings early on to complete the animal bundle fast enough. I will also have to have enough money to buy three apple trees and a pomegranate on Summer 1 unless the fruit bats have been particularly kind... Sharing here in case anyone else also wants to try it!