Entering score recipients on test day

Hello. I am new to the forum, but I think this is one of the best places with most comprehensive infromation, startegies and tips about GMAT. I will be taking the test in September, but I am little confused about the 5 school recipients that we can send scores to for free. What I do not understand is when exactly will I be asked to enter the schools - before I sit and start the actual test, or right after it ends? The asnwer to that will obviously make a huge difference. In most of the posts I have read, people say you enter them before you get seated and everything, but I remember seeing a post by someone in this forum saying that he/she skipped that option and then after finishing the test and seeing the score, was able to enter the recipients. I still have doubts about my schools to choose, because I don't want to enter schools from the top 10 for example, if my score won't be that great (better choose then some of the not so competitive and highly ranked schools). Also, will the school names be enough or I have to have their individual GMAT test code? If someone who has reliable info about this can answer, that will be great. Maybe it depends on the test center, where you take the test? Or not really? What do you think?