Far less than the adverts. A typical first year part time runs a few hundred pounds a month of contribution early on, building towards £1,000 to £2,000 a month by month 12 to 18 if you market consistently. The constraint is demand, not skill. Practitioners quoting £500 a day are describing established books built over years.
The honest pattern from delegates and from practitioners talking when nobody is selling to them: months one to six are quiet (friends-of-friends and slow referral), the middle stretch fills one clinic day a week, and somewhere in year two a repeat toxin book starts doing the marketing for you.
The arithmetic is in our earnings and salary report, with every assumption stated, and you can run your own numbers in the earnings calculator. Keep the day job through year one. That is not defeatism, it is how the successful ones did it.