This is exactly how contract work is done. If you’re doing this as a full time employee you’re underpaid (assuming it’s for your employer - doing it for yourself is a great idea!)
He wasn't our most productive or "rockstar" engineer, but he was highly organized, and I appreciated it.
I got a raise because I did this - I had hard numbers showing how productive I was for the year, and other devs didn't so he had to guesstimate their contributions.
I'm low tech and prefer to use a notecard with a grid on it, the squares of which bear enough space for only a word or two maximum, but you can just as easily use a spreadsheet or something fancier.
It makes putting together a better summary at the end of your day a lot easier, and it also helps with future forays into time estimation since you have a clearer picture of how long things take.
It also helps show when it's time to go take a walk.
> Set a timer to go off every 15 minutes
I realise this won't be a popular point of view with the folk who are always 'life-hacking' or what not, but my goodness that sounds mortifying to me.
I have worked in professional services too, and I had to bill for my time in 6 minute intervals, but I found it much easier to just switch between set of running timers when I changed tasks. No need to put together any timesheets at the end of the day, just note/submit the final times. I think a repeating 15 minute timer would literally cause me to go insane.
I'm all for people staying on top of their schedules, but I doubt that for most people the benefits of something like recurrent 15 minute timers could ever outweigh the costs (concentration, flow, mental health).
I use an Apple Watch, and it's a gentle tap on the wrist that's perceptible to me and basically no one else.
When I say "write everything down" I mean use the lightest of note taking. It can be a bullet point for the day, or an expansive note on a particularly difficult technical challenge, there is no one set way of approaching this.
The timer is pretty unobtrusive. It goes off, I write one or two words in a box, and I carry on.
The daily update in the spreadsheet is extremely useful though.
Keep a log of your work. In fact, keep a log of everything you do. It gives you a sense of accomplishment, it gives you an idea of where your year went, and it lets you refer back to key highlights during your negotiations for a raise or promotion.
You think your memory is bad? There is not an organization out there that will ever recognize anything you ever did beyond the last sprint planning session or Jira ticket you closed. I've yet to work for a manager, ever, that hasn't required a hard push to hit a deadline for months on end, only to then forget that effort and opine that you took off early on Friday. They'll remember the extended lunch you took yesterday, they'll forget you worked 19 days straight without a day off, whether it is a large tech organization or a small start-up of six people.
I am sure many of you will no doubt attempt to regale me with tales of awesome managers who made sure to give you "atta boy" pats and remembered that thing you did when it came to year-end review, but those stellar managers are few and far between, and most of us will never get to encounter such a rare shiny creature.
So don't be like all those times in college when you thought to yourself "I don't need to write this down, I'll remember it", because you won't.