I don't quite understand about timing yet. It's dinner time here and I took 4 units Novorapid before starting to eat. I'm eating 2 mandarins and a peach to start and then having 2 bowls of homeade pork/bok choy soup with a glass of 3.25% milk. A couple times I've hypo'd before even finishing a low carb soup so that's why I start with the fruit. Maybe this means that I'm bolusing too much.
It could be that you are bolusing too much but it could also be that you are bolusing too early. Also, you're maybe experiencing the inaptly named "honeymoon" period, where your beta cells start making insulin again for a while - it can really throw calculations out.
Timing is very personal and needs to be customised for each individual.
For example, I tend to bolus about 20 to 30 mins before a meal, in order to give the insulin time to distribute around my body so that it meets the glucose from carbs headon instead of playing catch up. But I'll adjust the timing depending on the type of food (less time for a low GI food), and whether I'm trending up or down (more time if I'm trending up or am at a highish level already, less time if I'm trending down and am at a low level).
With you hypoing before the end of a meal, it might be that, and I'm just speculating here, (a) you were already trending down at a low level so the insulin aggravates the low before the carbs get on board, in which case fruit at the start is an excellent idea to nudge it up before the insulin hits peak action, or (b) the beta cells are doing their honeymoon thing so you've got a double whammy of insulin from your pancreas and the injected insulin, and it all kicks in before the carbs catch up, or (c) you maybe just need less pre-bolus time than others do - it varies widely between individuals.
If your dsn hasn't mentioned it yet, look into cgm, like libre. Unlike strips, whuch just give a tiny snapshot, cgm gives a continuous trace showing how insulin and food are working together across time. We're dealing with a situation which operates over time, so actually being able to see it moving in more or less real time makes things much easier.
For example, in the pic below, at the left hand side at around 18:00 I can see the blue dots trending down, I knew that I'd be eating about 75 g, and I'd need about 9u for that, so I pre-bolused for what I thought would be about 20 mins, but the meal took a little longer to prepare than expected, about 30 mins, so there's a dip down towards 4 but the meal was finished off with a nice bit of dark chocolate cheesecake which would raise again, the sugar being buffered by the fat in the cheesecake and the barley in the Scotch broth, so I end up with a nice dip and rise instead of a spike.
Just being able to see how certain combinations of food and timing interplay makes it a lot easier. If course, T1 being T1 it still throws some random fliers, but I ain't showing those graphs, lol...