Thanks, armoured. I do have a few more details: we decided on a city, I already have a job (remote -- can be done from anywhere in the world). But nothing like an apartment rented yet, although we have already started looking at apartments and even houses -- I'll write a more detailed plan then. And I did find somewhere on another site that if you apply inland you need some kind of minimum salary, and I am a little under that amount right now.
Plus my partner can only stay in Canada for 6 months (typically) on a visitor visa, so if we go to Canada and apply after, then we will very quickly run out of that time -- and not sure what we would do after that.
-Job is very good, having even some searches for places to live / contacts with realtor etc good to, etc. If you're moving stuff, contacts with a moving company. You get the idea. It doesn't have to be all firmed up but planning / starting is what they look at. The job really helps and is strongest point - it might actually help if there was indication from the employer that they expect you to be based in Canada or near to their office within some period of time.
-You dont' actually need minimum salary to sponsor spouse under inland. That's a slight misreading of the requirements.
-As noted, your spouse can apply to extend stay, routinely granted for cases where spousal sponsorship in process.
For the 'intent to stay'/returning to Canada files (I did this), it's fairly clear that it does add an extra step internally, possibly a higher level of approval; what's not clear is whether that means an extra day or a few months (probably random / depending on things we don't know). If they're not happy with the intent to return stuff, they do ask for more info and that can add a lot of time.
As a very rough guess - I'd say if you're planning to move in less than 3 or 4 months, inland may be better; if more than ~8 months, just apply soonest you can from abroad. In between - no idea / flip a coin. (Others might have a better idea than I do, I don't follow processing times that closely).
Oh, one small additional point: if your spouse is applying inland, it's better if they remain in Canada once the process is started. Can apply outland (even if in Canada) if they expect to need to travel a lot.