Age as time scale

#1
I am generally a SAS user,

I had a general question concerning how to fit survival models using age as the time scale within R.

Would this fit be appropriate and also control for the left-truncated nature of the data? I know in SAS you need to specify a specific option. I was just wondering if you needed to do that for R too?

fit2 <- coxph(Surv(age, age+ time, status) ~ t5 + id, data = stanford2)