It generally takes between 30 and 50 days to get full benefits from the warm-up. And can go up to 90 days in some cases.
Indeed, this duration can vary depending on many factors:
The history of the inbox before the warm-up
The seniority of the domain
The email provider of the inbox
The activity of the inbox during the warm-up
The volume of warm-up emails sent/day
As rule of thumb, you can asses that the worse your deliverability is when you start the warm-up, the longer the warm-up will have to be to provide full benefits.
💡 Your deliverability can decrease over time if the warm-up is stopped. This is why we recommend to "Always warm-up your inbox".