Can the expression "be better off" be combined with "will", like "you will be better off"?
Yes, to "be better off" can be combined with "will". In fact, the sentence here actually includes "would", since "you'd" is a contraction of "you would". So the full sentence here should begin with "you would be better off". If you wanted to change the tense of this sentence to future tense, you could change this to "you will be better off". Ex: You will be better off applying to the job earlier since they hire people on a first come first served basis.