One way of thinking a lot of people have is, that they want to catch the absolute buttom, thats not possible oftentimes.
Instead the idea for today is:
Try to buy when the chance of it going "under water" (down from your buy) is the lowest. That is probably not the absolute buttom, but some point during a reversal, but before it already is reversing and will probably retrace lower again.
Buying when the chance of it going lower is the lowest and would also negate your opinion it is going up, has the advantage that you can have bigger position sizes as well. And if you are already in a long position thats up, it might be a good spot to increase leverage and add to your position.