There are a few exceptions to this rule, however. Some universities offer "accelerated" master's programs that allow students to complete their bachelor's and master's degrees in a shorter amount of time. These programs are typically more intensive than traditional master's programs, and they may not be available in all fields.
In addition, some universities offer "joint" bachelor's/master's programs, which allow students to earn both degrees simultaneously. These programs are also typically more intensive than traditional master's programs, and they may not be available in all fields.
If you are interested in pursuing a master's degree, you should first complete your bachelor's degree. However, if you are certain that you want to pursue a master's degree, you may want to consider an accelerated or joint bachelor's/master's program.