You're right. But that doesn't explain how he'd have been trained on the new design by the time TSFS rolled around.
What do you mean, "new design?" Aside from the out-of-universe replacement of the original film projectors with video monitors, the bridge stations in TSFS were the exact same ones from TMP, which means they'd been unchanged for at least 12 years. And Reliant
had the exact same design too (since it was a redress of the same bridge set). Do you really think that Chekov got from security chief to first officer without ever training on the science station?