It's never too late to start and it's never too soon to quit

It's never too late to start and it's never too soon to quit
 

For "It's never too late to start and it's never too soon to quit" I just made up

Nunca es tarde para comenzar, tampoco temprano para abandonar

but would like to hear any better way to say it. It's a good thing to say.

It sounds OK. Maybe you can say no existe un tiempo inoportuno para aprender
ni para abandoner sus estudios.--- or something like that.

I propose "...ni demasiado tarde pronto para renunciar".
"Temprano" is normally used for "early" when talking about hours of the day, and "abandonar" needs the complement "¿abandonar qué?"

Nunca es tarde para empezar ni pronto para abandonar.

Thanks to both. I can use both suggestions. Hey aleC, just out of curiosity why empezar instead of comenzar?

Regional and personal preference. To me empezar is more related with having a beginning and comenzar more related with beginning, though are almost interchangeable:

La función (de cine, de teatro) comienza a las 9 y termina a las 11.

Nunca dejes sin acabar/terminar lo que empezaste.