[Captain Ahab Jr]

Some very good advice,

Have you thought about taking on short term freelance engineering contract work not working a full week or working say a 3-6 month contract. If there is enough work around you should be able to switch on/off your day job income to suit your business

I'm a freelance design engineer and this is my approach but I choose the interesting jobs before chasing the last dime. Last summer was spent at home building, now I'm working 12 hr days which don't feel that long as I'm enjoying work. This plus 2hr commute, having a family, weekends man cave building, holidays abroad leaves me no spare time, just how I like to live,

Also maybe think about ditching some of your other distractions (not including your girlfriend) while you concentrate on building your business and day job as/when required. Spreading yourself too thinly will just mean you'll be doing everything badly.

You're only 24, got a whole life of time ahead of you so as others have said you have time on your side.