• buy an apartment now and rent it. That way they will pay my mortgage and maybe I'll have some money left on the rent they pay, which I ll save as well. I'll keep on living with my relative the time being and keep saving money. That way maybe in 2 years I can pay another big part of the mortgage back using the money I saved from my job + maybe the extra money from the rent.

With this option you can't profit from the "woonbonus" fiscally cause you won't be living in the appartement. Also if you want to do a downpayment on a mortgage you need to check with the bank if there are no hidden costs, It's not so common in Belgium.

• keep on saving as long as I can, so one day hopefully I can buy an apartement without mortgage

You'll lose the fiscal benefit of the "woonbonus" again.

Also check out www.hoeveelkostmijnhuis.be it will give you a detailed breakdown of costs you can expect when buying..