kayancdh,

I can never estimate when exactly the new wetsuits become neutral cause of a few factors.
1) The brand. Better branded quality wetsuits have longer positive bouyancy.
2) How you control your breathing and adjust to the new wetsuit. You may use 3kg and can add another 2kg but other individual are different from each other. I encountered so many time divers who thought just by adding 1 or 2 kg more can have negative effect but not.
Some divers have difficulty adjusting their breathing when they wear the suit and their bouyancy totally out underwater.
Your chest becomes compress when the suit is on and thus just by a small breath of air can allow you to be positive so easily.

Best to know your weights is try the suit on before any dive trip. Go to the pool. Get the feel. Do bouyancy check.
After you know your pool weight. Just add another 2kg in salt water on the 1st pre-check dive at sea.
Yes you can be very negative but this pre-check dive allows your suit to absord the saltyness of the sea and during this
pre-check dive you can know your bouyancy whether to keep any additional weights or let go a few.

It is better to be a little bit heavy rather than dangling on the surface requesting at the boatman for additional weight. worst when there are no additional weights on board.

Hi Kayancdh,

Guess it would be 3mm full suit,what they suggest were right, new wetsuit or any neoprene materiel which is new will tend to ve positive buoyancy "Function". Beside having tested in pool, I ve few suggestions for yr reference,

1.  If u ve no time to test in pool, try to soap it for few days at home, can add some salt & few drop of "Dettol"(not too much ) into it, rinse, make sure the material absorbed the water, this is due to neoprene has a layer of wax on the surface, u can't wash it way but it will slowly go off after u wear few time. This trick will help a little bit but not entirely.

2.  Like what Run said, carry extra weight, 2kg extra would be good, u just ve to make sure u control yr descending rate make sure u r  fast enough to equalize yr ear. But once u were down below, u will feel slightly heaver, than just slightly inflate BC, while u r accenting to a shallower depth, make sure u inflate yr BC, try to stay as low as possible while in shallower depth.

Just to share. I had once wore a 3mm new wetsuit and did a nite dive during the first time wearing it. I stick to my usual profile with 3 kilo weight. Have no prob with it, Alhamdulillah.

My point is, ability to tailor one's breathing is a very important contributing factor during a dive. Yes, I'm agreeing to the idea of a personal check-out dive at the pool. I find it very helpful. Apart from serving as a refresher session, we can also tailor our profile according to the new elements we are having in our dives later on.