The estimated time for your body to get into ketosis is estimated to be 1-3 days. [1] Although it can even extend up to 10 days [2] or more than a month [3] depending on how your nutrition was prior to starting the ketogenic diet.
The body enters ketosis when it switches using the primary energy source from glucose to ketones. [1]
[1] How long does it take to get into ketosis – Healthline
[2] How long does it take to get into ketosis – My Keto Kitchen