Dear aspirant,

The tentative dates for filling forms for 11th standard depends on the board and the state you're applying in. Most CBSE schools begin admissions in the May, after the results of class 10 are out. So it usually happens in May. To know the exact dates please mention the state and board of the school. You can visit these links for more information.

Thank you

https://school.careers360.com/articles/maharashtra-fyjc-admission

https://school.careers360.com/articles/kendriya-vidyalaya-admission-form