This flashback takes place minutes after the "first transformation" flashback we saw at the start of Chapter 6. Shortly after seeing himself for the first time in the mirror, a giddy Hyde tottered out of his laboratory, across the courtyard connecting his laboratory to his house (not yet depicted in this comic, but the same one as in Strange Case), and attempted to hop over the metal fence to the street. He missed and fell into some bushes on the basement level of the house.
On that note, I should mention that the kitchen in this scene is the one located in Jekyll's house, not the Society kitchen, hence the altered layout. Rachel was Jekyll's personal chef and maid before becoming the Society's cook and day manager.
Please read the "Freeeeeeehahahahaha" in the voice of Anthony Warlow from the 1994 concept album of Jekyll and Hyde. You are welcome to imagine the musical accompaniment there as well, provided it ends with a record scratch or some other equally silly way at the "oof."
Combining notes 1 and 3, you are also welcome to imagine Hyde using Anthony Warlow's "freeeee" while doing the body motions of the cat calculating the jump in this video.