How much does your FTP increase week-to-week?

The physiology that leads to increased FTP doesn't really show noticable changes on a week by week level. At the beginning it's not unsual to see big gains as you get accustomed to harder riding and test efforts and your sustainable power for a test duration can increase or decrease week to week based on freshness, having 'blocked up' legs after too much rest, diet, hydration, motivation, etc.

Most folks with a season or more of solid training under their belts would be happy to see FTP climb by 5-7% annually.

Short term increases or decreases in sustainable power don't generally reflect actual FTP changes, but in a sense it doesn't matter that much. You were able to sustain higher power this week than last and whether it was just a better day to test, better freshness, better motivation or your body getting used to sustained hard efforts the bottom line is you're seeing progress.

FWIW when I first started training with power I added 60 watts to my sustainable half hour power in the first six months or roughly a 27% increase. Since then I've increased my sustainable power by a bit more than 3% per year for the last three years.

-Dave