My philosophy is that everything is built on fundamentals, so it follows that getting faster at typing help you get better at programming-- especially if that helps you get into flow.
Two things matter when programming, comfort and speed. Comfort means you might experiment with different boards and speed means you need deliberate practice to get better at those layouts.
For customising, I've been using a custom layout 
for my Ergodox EZ, but more recently I've been playing with the QMK Firmware directly.
For deliberate practice, I've found Peter's Online Typing Course really good. It gives you different levels to practice at that build on each other, and statistical feedback about your speed so you can watch yourself getting faster. Website