Not everyone can do this, but if you can manage to first do contract work, IMHO it's win-win for both parties. From the company's point of view: senior engineers are very expensive -- having a contract period lowers risk. From the employee's point of view: you get a good idea of what the company is doing / what your exact role would be before you commit.

In theory, it's at will employment yada yada. But in practice, it makes a difference.