My advice is to really work out the value proposition. How much value is the first employee going to bring when it comes to revenues and how fast will those rev

My advice is to really work out the value proposition. How much value is the first employee going to bring when it comes to revenues and how fast will those revenues materialize? $5k just isn't that much money but if it feels like it will over-stress your business then maybe you are not ready for an employee and need to keep progressing the way you have been even if it means you move slower than you would like. The other option I would consider is contracting out some projects to the experienced engineer if he is open to it and discover more about what he can do, how he can help, and get a real feeling for what he will bring to the business.