Ah bueeeno, con esto genero las fechas en un rango. Ido de podeeer
function! GenerateDateRange(start_date, end_date)
let start = strptime('%Y%m%d', a:start_date)
let end = strptime('%Y%m%d', a:end_date)
let dates = []
while start >= end
call add(dates, strftime('%Y%m%d', start))
let start -= 24 * 60 * 60 " Subtract one day in seconds
endwhile
call setline('.', dates)
endfunction