Special_snowflake
Thanks for the chapter. That depend what you plan for the training, if it's only training then you can just skip it. If not, you can make a time skip of a few month at the start, make an arc to see his increase in power during the first half (some pirate arriving on his island, getting his first crew members and training him for the next part of the time skip, or something else), then another time skip to start the adventure. Then during the following arc you can put some flashback of him fighting beast to unlock different power or something.