Neurulation is completed on day:

Closure of the cranial neuropore occurs at approximately day 25 (18- to 20-somite stage), whereas the posterior neuropore closes at day 28 (25-somite stage). Neurulation is then complete, and the central nervous system is represented by a closed tubular structure with a narrow caudal poion, the spinal cord, and a much broader cephalic poion characterized by a number of dilations, the brain vesicles Ref: Langman's embryology 11th edition Chapter 5.