Welcome to the club
Actually the next few months are going to be cloudy with some scattered clear nights.
I'm not familiar with the Tiong Bahru sites but generally that close to the CBD the light pollution is going to be quite heavy anyway.
You'll probably want to find a spot that is decently dark (and safe) so you get some amount of dark adaptation. Also looking away from the direction of the city may help since that's where the worst light pollution is.
However, the best scope is one that is used the most so even your hall/bedroom window is a good choice!
I know there's a park nearby where they did a shootout of 2 large scopes a few months back.
Other places include Labrador, Mt. Faber/Telok Blangah hill park (you may have more to see than stars!)
Generally with a 3" achromat, you'll probably be looking at bright targets like the moon, brighter star clusters (check out the Peliades and the Orion group), appreciate the different colors of the stars and the planets. Even then, there's a lot to see that can be seen!
Have fun!
P.S. Why not join the sidewalk groups when they are having their public viewing? I know's there's a 70 or 76mm Celestron there as well at the Bishan Park/Toa Payoh group
A bit far but not too bad via MRT
