If you have to ask the question 'How long does it takes'.
It begs the response 'Do you know what you are doing?'
Brake line connections are notorious for sheering off at the connection nut- unless you are very careful. Also you will naturally end up with a loss of hydraulic fluid- Do you know the right order and how to bleed air locks out of the master cylinder and brake lines. Do you know which 'spec' of hydraulic oil your vehicle uses.
Please get yourself a manual for this type of job because I dont want to see you in my rear view mirror nor in a Coroners Court.
GB in Wales