if Conventional current is wrong
Conventional current: used by engineers and physicists everywhere. It's what's measured by ammeters! It applies to all circuits, including the non-electron flows in dirt, nerves, acids, plasmas, etc.
"Electron current:" used by technicians during WWII ...and by several generations of students taught by them. Applies to solid metals, and especially to vacuum tubes. It cannot explain nerves and batteries, semiconductors and plasmas, or any situation where proton-flows or mobile ions are paramount.
In other words, electron current is wrong. Don't use it. If you have a textbook which employs backwards current (electron current,) just throw it away. Heh, or perhaps chop it up, so it cannot harm anyone.
how can I trace the flow of current in a schematic?
To understand circuits, we don't trace the flow. (After all, batteries don't spit out constant current.) Instead, we study the schematic as a whole, and determine the pattern of voltages across the various circuit points. Then, knowing the voltages, we can figure out the current in any component.
"Tracing the flow" doesn't work, since it isn't based on Ohm's Law, and it leads to mistaken thinking. For example, at any "Y" junction, how do the charges know to split up? How do they know which path to take? They don't. Instead, the voltages far downstream are determining the current in the entire circuit.
Also, to visualize the flow, we DON'T start at the power supply. After all, the wires are already filled with electrons. Current is like a flywheel or drive-belt, so we can start at any point on the circle. That's why the currents aren't simple and obvious: a schematic is like a bunch of flywheels, all loosely coupled together and spinning at different rates. (A battery isn't a source of electricity; a battery is actually an "electricity pump.")
If tracing the flow doesn't lead to understanding, then what does? Ah, that would be voltage, as well as the voltage-dividers scattered throughout the circuitry. The goal of electronics students is to learn to "see the voltages" all throughout a schematic.
One education site which goes into the voltage-divider viewpoint is NCSU/Williamson:
Also check out Falstad's java circuit simulator, where voltages are shown as colors. Here's the animated guts of a 555:
ALso see his entire circuit-animations index.