I don't have an answer, but you can't just leave us hanging. What's it smell like?
If you can get out of the place for a few days, sealing it up tight and having an ozone generator going full blast works really well at getting rid of bad smells. If that's not an option, I'd recommend making an air purifier like this one.
I'm Canuckistani. No-go on an air filter either? If we're going mad low rent, you can make a carbon air filter on the cheap by doing something like this with the pre-filter
A Corsi-Rosenthal box is a good thing to have around long term, but it won't really help with the bad smells as MERV 13 filters can't filter out VOCs.
Understandable. Sucks to not have family or friends nearby you could crash with. I'm in a similar situation after moving across Canada recently. Incenses might cover up the smell or just combine with it, but someone sensitive to these things would still have an issue because the source of the problem hasn't been solved. Try and get some activated charcoal, or just regular charcoal, as that can actually absorb the bad smells.
The paint smell and "old building smell" are caused by Volatile Organic Compounds. The paint is offgassing these compounds and will continue to do so for months or years, though the bad smell will lessen in a few weeks or so. The "old building smell" is caused by microbes, and can be reduced in the future by regular and deep cleaning of the place, especially in areas that people are unlikely to clean: up high, behind things, or in things. The best way to get rid of the current bad smell is to get those compounds floating in the air out of your apartment, either by sequestering it into charcoal which you then throw away after maybe 6 months, or by circulating air out of the apartment by opening the windows.
You have to get this bad smell out to get a good smell in.
The problem with bombing a new scent in is that combining scents can end up worse than the original stink you were trying to cover, especially to the noses of sensitive people. Do you have any idea about the source of the stink? Different types and different locations of stench have to be fought in different ways.
Are they going to paint your apartment? If they haven't yet, there are scents that can be added to the paint to help cover smells that have soaked the walls. Your landlord probably won't spring for it, but I think they were around $10 when I saw them while buying paint for my chicken coop, so maybe you could ask if they'd be willing to use them if you provide them?
Carpet stink can be a lot harder to deal with, it'll almost certainly take repeated attempts and maybe enzymatic cleaners, but doing it before the place is full of your stuff is a lot easier. Would it be possible to rent a carpet machine for the day you move in, and go over the carpet in the morning before you start bringing in the furniture in the afternoon?
In the US, sage smudges are usually with incense and candles in a store, so if you're not seeing them when you shop for those things, maybe they're not available where you are.
It sounds to me like you're already doing all the right things. I think the smell issue will be gone within a few weeks of you living there, moving air in and out, and cooking in the place. If that's not soon enough, I think your original plan of candles is probably the best one.
You could try to air or dry it out. Open windows, crank up the heat, let the sun shine on surfaces so the chemicals vaporize away.
Ofc if you have washable or cleanable surfaces, you just need to clean those.
Finally add your good scents to replace the lost layer of compounds. I don't think candles and sprays are very good, those compounds don't really travel in the air as I understand. Maybe try incense, or cooking some desserts.
I've done some of this to air out my place after some pungent cooking
It can be difficult to remove some smells so the answer is, "it depends".
Either way, you can try (1) cleaning, (2) using smell-absorbing stuff and (3) lighting a nice candle or nebulizer.
If there is already a smell, you've gotta clean. The smell us just chemicals embedded in surfaces that are popping off due to volatility. Surfaces can often accumulate and become saturated with smelly chemicals, like when someone repeatedly smokes indoors. Cleaning those surfaces can fix some smells by removing the chemicals.
You can also use smell-absorbing stuff like baking soda. It's an abrasive so be careful, but if you use it when cleaning surfaces it can really cut the smell. Fans/air purifiers with activated carbon filters also help.
For candles and such I'd say... go light. Just a hint of the smell. The person coming over might dislike a strong candle scent more than your adjustment's current smell!
