Hey mama! I haven't personally tried Fabella, pero one of my mum friends goes there regularly and she just walks in sa morning or calls their clinic directly to book, super convenient sya sayang kasi walang hassle with online systems doon. Best ko sabihin is tumawag ka na lang sa Fabella mismo para malaman mo exactly ang process nila at available slots, kasi bawat branch might have slightly different setup, plus mas mabilis and direct yun kaysa mag-Google around hehe. Let me know kung kumusta sa experience mo there!