I'm on twice a day mixed and it's very easy. Before breakfast I always check my bg reading and at the same time get my insulin pen ready. Just before my toast, yes toast, as I'm a T1 I don't have to do LCHF, my pen is there on the counter top, I can't miss it. Same procedure before dinner, bg test, pen ready where my plate will go. Very occasionally I realise I've been too eager to eat dinner and the insulin has to be injected immediately after, but so far I've come to no harm. As
@Daibell says, It's really about getting into a set routine and it soon becomes a habit.