When you can afford it. first do some research, looking to see how much rent is in the area you want to live. Can your current salary/wage pay for that? be sure to include utilities, parking etc which may be extra.
Then call the place and ask how much to move in. This is important in that many places require a first month, last month AND a security deposit at the time of move in. You would need to save up this amount before you move in. at the same time as this call, you can ask any other questions such as security in the area, rules about noise, etc.
A rule of thumb is you should have 5-6 months of rent in the bank before you move in. You may end up paying 3 months up front, and then need money for deposits on utilities, furniture, and even dishes.