It's still recommended to buy not yet late but the biggest opportunity was last year when Bitcoin was trading at $6000 to $7000 level, but like what I said it's not yet late as long as you are buying before halving you are in a good profit after the halving, that is if you can hodl your portfolio and sell it at the right time.
It's never too late to buy Bitcoins, even after the halving. I do not expect the price to skyrocket after the halving, but Bitcoin is unpredictable and all we can do is speculate. But I do not sell the idea that by simply buying before the halving you're going to profit.
You pointed out selling at the right time and that I believe is the best quality of a trader or hodler. Timing is the all important factor in trading; long or short term.
That's the good thing with bitcoin which is very unpredictable like you will not notice that can earn good profit by just buying on it, but take note not all the time you can gain by just buying bitcoin. I agree with you that all we can do is to speculate but by just doing this kind of stuff you can prepare yourself on earning good profit or losing a huge amount of money. Just like what I have said in my previous post that we still don't know what will gonna happen to the result of bitcoin halving. I like your idea that buying bitcoin before halving and it might be applicable if you going to buy now. Although we are not sure about profit it still good if you are ready for its result.
As long you can gain income from selling bitcoin it might be the best time to sell but if we considering the huge profit that we intend to gain maybe you should wait patiently like it will hit the highest price on the market and I agree that with proper timing of selling will lead to you a good profit.