Moving is an afternoon's work, and nothing has to stop on day one: bookings already made in your old system can finish there while new ones come through your FullDiary link.
Start with your customers. In your old system, open the client list, look for Export or Download and choose a CSV file - Fresha, Booksy and most spreadsheets work. In FullDiary open Customers, press Import from a spreadsheet, choose Another system or a spreadsheet and pick the file. Names, phone numbers, emails, dates of birth and addresses come across, and so does the date someone first became a customer when your file has it. You see how every column is matched and can change it before anything imports. Anyone already in FullDiary is matched rather than added twice, a row with no name is skipped and listed with its line number, and running the same file again adds nothing new. Up to 2000 customers a file, on every plan.
Coming from Cliniko? Choose Cliniko instead. In Cliniko, open Settings, then Data exports (you need to be an Administrator), and export Patients, Treatment notes and Attendees, plus Calendar events for your blocked-out times, from Any time to Any time in the Data file format. After your clients come in, each treatment note becomes a private note on that customer, dated on the visit, and the appointments follow: upcoming ones are booked with their reminders, past ones become completed visits, and blocked-out time stays blocked. Switch Cliniko's own reminders off so nobody gets two.
Then set up your booking page: six quick questions with the answers filled in for your trade, and it goes live at the end.
Bookings you already have go into the diary with Add: who, which service, who with, the day and the time. For a regular, set Repeat (every week up to every 8 weeks) and their slot keeps itself. Switch your old system's reminders off for anyone you move across.
A patch test or consent form someone already did with you before the move: open that form on their profile and press Don't require for this customer, so they are not asked again.
Gift vouchers you sold before: press Issue a voucher and choose Bought before FullDiary, then type the old code, what is left on it and its use-by date. The customer spends it exactly as before. Gift vouchers are on Pro.
Last, put your new link where customers already find you - your Google Business Profile, Instagram and Facebook bios, WhatsApp and the QR card by the till - and new bookings start landing in the diary.