When determining the number of options to give to the first non-founder employees, it is recommended to give them 3 times their forgone salary in stock.
For example, if an engineer's salary 'should' be $120k but they work for $60k, they should be awarded $180k in stock for each year they work.
However, this may not fit within the company's valuation, especially for early-stage startups.
The general rule is to estimate the equity the employee would have if they joined later and try to triple it.