While both 8 and 88 have been used by Grosjean and Kubica respectively, they are available now by default. Grosjean last used the number in 2020, Kubica in 2021. F1 Drivers were free to claim these numbers for themselves from 2023/2024 respectively.
For now Perez last used his 11 in 2024 (I dont believe he used it in his Ferrari test, or at least it doesn’t count), which means it would be free to claim in 2027.
While both 8 and 88 have been used by Grosjean and Kubica respectively, they are available now by default. Grosjean last used the number in 2020, Kubica in 2021. F1 Drivers were free to claim these numbers for themselves from 2023/2024 respectively.
For now Perez last used his 11 in 2024 (I dont believe he used it in his Ferrari test, or at least it doesn’t count), which means it would be free to claim in 2027.