32 Year Old never invested before (Canadian)

** Yes, I used ChatGPT to help me write this post:

Hi everyone,

I’m a 32-year-old guy, married with two kids, earning about CAD 9,000/month after tax. I’ve been aggressively paying down my mortgage and am excited to share that I’ll have it fully paid off by the end of the year. Once that happens, I’ll have around CAD 6–7K/month in liquid funds—for the first time, I’ll have real cash to invest.

Here's where I stand:

• I currently have CAD 0 in investments—never bought a stock in my life.
• I recently signed up for Wealthsimple and have a basic grasp of how TFSA and RRSP accounts work.
• My only asset is my home; I don’t yet have anything in TFSA or RRSP.
• I work for the federal government and have a defined-benefit (DB) pension plan. I’ve been there for 10 years and likely have another 25 to go, though I’m not 100% certain I’ll stay for the full duration.

I'd appreciate guidance on a few points:

1. Where should I start? Should I just open a TFSA and funnel a set amount into an ETF like ZSP monthly and “set it and forget it”?
2. Do I prioritize TFSA over RRSP (or vice versa), especially given that I'm in my prime earning years but might pay less tax in retirement than I do now?
3. Since I might move in 3–4 years, sell my home, and buy a slightly bigger one, should I keep some liquidity or invest with flexibility in mind?

Any advice, whether it’s simple strategies or pointing me toward the right ETF or account type, would be incredibly helpful. Thanks in advance—I’m ready to make this first step!