I believe that swaying, at most, ever-so-slightly tweaks the odds, but only in the order of fractions of a percent. You have a 51% chance of conceiving a boy and a 49% chance of a girl if you do nothing at all, but because of the way that sperm are formed in the testes, you're not going to have a significant alteration to those numbers unless there is a genuine medical condition that affects one or the other (of which I can think of none!).
What the mother does is also unlikely to have a massive effect. After all, even altering pH is not going to work perfectly - there are literally millions of sperm, and so some of each will definitely get through regardless. The same thing with timing - yes, it may have a slight effect, but the effect is not going to be so significant that you can really count on it producing the results you're after.
For every successful sway, there will be someone else with an unsuccessful one. That kind of tells you the odds.