Hi Vicky. The S9 has been getting updates for the past 4 years and moved to a quarterly update cycle last year. Samsung have said they will support devices for a maximum of 4 years so that means the S9 is now past its End Of Life (released 16th March 2018). Some have reported an update in the past couple of weeks but as with all Androids, different carriers take different times to actually push it out. Whenever you get it, expect this to be the last update you will get for your S9. Sorry!
Will it be unsafe? Technically yes because any security holes will no longer be patched which leaves you vulnerable. Practically I would say not for the time being. You would still need to be targeted by someone and unless you're on some hacker or state hit list then you should be OK. As the phone gets older and more and more vulnerabilities remain unpatched, your attack vector gets bigger and the risk increases. How much risk you're willing to take is a personal choice and you will have to weigh that up for yourself I'm afraid.
There's no set time period that you will be safe for. A major vulnerability may be discovered tomorrow which leaves you very unsafe. On the flip side, it could take years for anything major to come along. Hackers hoard vulnerabilities (known as zero-day vulnerabilities) that they could use right now and it doesn't matter if you have the latest patch or not. The thing that will keep you safe right now is that you are unlikely to be a person of interest (unless you're a politician or an activist or maybe a celebrity).
Thankyou for the reply. Samsung told me that knox keeps it safe but I'm going to look into getting a new phone st some point, but my s9 plus is powerful and I don't want to downgrade but the price of the new ones is too much at the moment I'm payg so limited funds.