Spanish nationality

Hi SIR
I am 24 years old and living in spain for last 5 years.
I came here through * Family Regrupacion* option because my father was living here for 9 years .
When i came here , i got the residence permit with my father because i was less then 18 .

NOW
This year my father got nationality .(10 years ) .
My brothers will get the nationality as they are less then 18 .
Now
My question is that
WHEN CAN I APPLY FOR SPANISH NATIONALITY ?
IS THEIR ANY WAY THAT I APPLY IN LINK WITH MY FATHER OR SOMETHING.!!!!

i hope that you understand my question .if their is any ambiguity then please ask me .

Please reply me soon .

Thanks