If you want a full time home leave after one tenure then it can be sanctioned by your seniors in a time period of 2-3 months and can be extended for 15 days from the end date of allotted leave.

Although this rules can change depending on the situation and requirement of officers but in general this is the regulation (as per the information available online)

To know more about IFS as a career choice then visit the link below:

https://www.careers360.com/careers/indian-foreign-service-officer

To know more about UPSC visit the link below:

https://competition.careers360.com/exams/upsc-civil-services-exam

I hope this answer helps. All the very best for your future endeavors!