If only I had is usually said when the impact of what you were supposed to do or say previously would have been effective before than now.
It’s either you hesitated or postponed an action or saying, it’s now a thought not vocalized or action not implemented that is good as useless. Doing or saying what you can, when you can and while you can is important because the next moment is unknown.
After reading Richard Branson book “screw it let’s do it,” I saw the importance of not being hesitant to take action nor to say whatever you want to say. Excuses and over thinking is just a waste of time. Some would sum it up as being and living in the moment as you tackle life situations.
However majority of the people are either day dreaming nor blame it on the alcohol or stress and just end up saying “if only I had,” regrettably.
Rather say I said so, did so and its history fully explored. Do not be haunted by if only and what ifs.