Also question regarding going to landside. I have similar self connecting scenario, TK54(T1) to TR430(T2) without checked luggage, 2HR10MIN. I know if TK54 isn't delayed and I'm allowed to carry hand luggage then it's no issue.

So, how much additional time would be needed to clear immigration both ways? My transit time is 5:30pm - 7:40pm. I just need to factor in scenario if I'm required to check in my bag.

My passport doesn't require visa into Singapore.