My suggestion is use whatever branches, leaves, or even entire green logs you have this year on the bottom. Add soil into every possible crack & onto the top. Then start planting. A large percentage of nitrogen fixers for the first couple of years is recommended. The amount of
wood & other organics & how fresh it is partially determines how long it takes to completely break down. A full scale hugel will take 20-30 years. That's basically the point ... do a lot of work up front & very little in following years. Good luck & welcome to permies.