Davo, how many properties does the £740 of work consist of?
Apart from your conservatory price it is unclear how good the work you have is without knowing how many jobs you need to do for £740.
£740 of regular cleans (20-25 hours work)
£350 of one off conservatory cleans ( 4 jobs 8 hrs work max - may stretch it)
i'll start off with the bad news, i believe your figures are way out on the income for the hours worked. If your employee is gonna achieve those figures in that amount of time with no experience you will spend your next 20 - 25 hours recleaning them.
You have taken the figures and the cream prices and came up with your answer. The reality will be very different for several months at least.
Am i wrong by thinking that you haven't done a weeks work cleaning windows yet? As your 1st post suggested that you hadn't. Are you wfp or trad? I couldn't work it out.
Your post does appear to sound like a fairytale beginning with bells on. Because of that there will be some on here who will shoot you down, while others initially sit on the fence and then join in.
Ignore that "us and them" sh!te. Many will read your posts with as much interest as they do others, regardless of what the self-proclaimed 'elite' might claim. :

Oh yeah, regarding your post title, competition isn't dangerous or even threatening to anyone who is doing a good job, reliably. There has always been and always will be competition, it is what makes us richer.
Best of luck with what you are doing and do keep posting updates on your situation, we can all learn a bit from your posts as you have gone straight into employer mode without being a window cleaner yourself 1st, which is very unusual.