Hi Pikato,
This isn't a professional training schedule- it's just how I got from 35 miles to 100.
On Saturday I would ride a long ride. For you, let's say 30 miles.
On Sunday I would ride half that distance. 15.
Monday rest.
Tuesday 15.
Wednesday 15.
Thursday 15.
Friday rest.
Saturday 35.
Sunday 15 or 20.
Monday rest.
Tuesday 15.
Wednesday 15.
Thursday 20.
Friday rest.
Saturday 40.
Sunday 20.
So increase the long ride by 5 miles a week on Saturday, and the Sunday ride is half.
Then a couple rest days during the week, and ride 15-25 miles on the other week days.
It got hard for me in the 60-75 mmile range, then easier at 80-85. When my mileages were higher, like 65 or 70, I'd increase 10 miles on the long ride. I had to be really careful to get enough to eat toward the end of those rides. I learned a lot about nutrition!!
I think my last long ride before the Century was 90 miles. I didn't worry on the Century that I could go 100, but it was still scary because it was my longest ride ever!!