It's not an ideal world and there are pros and cons for everything.
Ideally you cannot burn the candle at both ends. So you can't carry on getting up at 5am and still be bright and thinking straight at 2am. You certainly can't carry on like that for a minimum of 3 weeks. So, unless you have help you maybe need to rethink your system.
I used to lamb 100 sheep on my own with a minimum of difficulties. but you have to accept that you can't be there all the time, so you have to have faith in the sheep. If a ewe's lambed before and raised her lambs ok then there's no reason why she shouldn't do it again without any need to supplement her colostrum. An old farmer I knew only lambed ewes that had been proved as mothers as he accepted that the times of staying up all night were past.
So - as for colostrum - I would accept that the best is from one of your own ewes (if available) and next best is goat's, or powdered. Cows colostrum is better than nothing. I've used it very successfully so I'm not knocking it - though some do. As for how long a ewe produces effective colostrum - I reckon that as long as it's yellow and looks like colostrum, then it'll do the job. I've milked a ewe the day after she lambed and still found it worked ok.
Whether to give a lamb a colostrum supplement depends on the ewe. If you've reason to doubt a ewe's suckling ability - like she's very flighty or pushing a lamb away, and you are almost asleep on your feet then give the lamb something and get off to bed. You know then it won't die while you're asleep and you can reassess the situation once you've had a break.
A useful tip I read, which seems to work (at least partly) is that if you feed the sheep late on - like just before bedtime - they tend to lamb in the morning. If you feed them early morning, then say in the afternoon, they tend to lamb at night.