I have done this for some years fairly successfully. Bear in mind that people who dont farm have no idea of your timetable, be prepared to have people turning up on spec to see their pig, (mostly at weekends) often bringing another dozen (no exageration) people with them; and have plenty of teabags and biscuits ready. As long as you like people and are prepared to go the extra mile to make them welcome it works well. Take a deposit, draw up an agreement in writing, and imho its best to be clear as to what weight of meat they are expecting from their pig, and to agree beforehand who organises the butchery etc. Dont underprice yourself, pig food has shot up this year. Allow a small percentage in case you need a vet, and in the very worst cases, make sure you have a spare pig just in case. (Hope this is never needed). Its good fun, you should make a small profit and if they do back out (and some do) you will be left with cheap and delicious pork.