MMR stands for measles, mumps and rubella. Most doctors administer it at the 12 month's well-being checkup. You sure can ask to delay it, but please be aware of the risks based on your baby's circumstances. According to the statistics, around 1 in 10 babies will develop a fever 7 days after the vaccine injection, which normally lasts for three days at least.
Bless the feaver will go down to normal about 3 days, when my son took. so don't worry too much. But after feaver, there'll be a couple of red rashes on the face or body. It's normal too.