A possible route plan for the large Archipelago ring bike route starting from Turku in a clockwise direction can (depending on fitness) consist of e.g. 4 day sections, provided that campsites are used:
Day 1: Because I was coming from Helsinki, I drove 23 KM or around 1:20 from Turku to Camping Solliden (solliden.fi/) in Pargas/Parainen Day 2: Camping Solliden to Camping Kittuis (kittuiscamping.fi/) is around 64 km or 4 hours. Day 3: Camping Kittuis to Camping Livonsaari is 90 KM or 5 hours (livonsaarencaravan.fi/). Day 4: Camping Livonsaari to Turkku is around 40 km or 2.5 hours on the last day - then you can also travel back to Helsinki
An alternative campsite for day 4 would be a campsite in Mussalo, which would have shortened day 3 a bit (sfcmussalo.fi/)