It takes around 10 minutes to mine just one Bitcoin, though this is with ideal hardware and software, which isn't always affordable and only a few users can boast the luxury of. More commonly and reasonably, most users can mine a Bitcoin in 30 days.
To put it another way, you would need to use specialized hardware called ASICs (such as Antminer S19 Pro), with a hash power between 95 and 110.0 TH/s. These devices can cost up to $17k. With 5–10 ASIC miners, you can mine 0.01 BTC per day. But to get one BTC, it would take about 100 days of mining.