From my own experience, mistakes and testing over the past 6 months, I have come to the conclusion that all TDS meters are completely inaccurate
unless you have recently calibrated them yourself with a good quality calibration solution. So, unless you have done this, don't be surprised if the actual TDS of your "200 ppm" water is somewhere between 150 - 250. They can be that out, maybe even more!
So my advice is not to use TDS to determine the amount of SS minerals to add to your RO. Instead, use a GH liquid test kit to keep testing the water as you slowly add the minerals keeping track of exactly how much you have added (by weight is preferable for accuracy, but you need a set of small precision scales, otherwise get a small spoon and record how many spoonfuls you add). Once you hit your target GH, then test KH to confirm that it is half the GH (which is the ratio of SS GH/KH+ from memory).
Only now once you know how much minerals to add to your RO water by weight or spoonfulls to get to your desired GH should you measure the TDS. This TDS reading is however completely arbitrary and unique to you, so you cannot compare it will what it says anywhere online. But (providing you have a decent quality TDS meter that is stable and gives repeatable results), this will be your target number for each subsequent time you make your water.
Just checking - you have inert substrate right being as though you are using GH/KH+ ? If you have active soil substrate you don't really want to be adding KH otherwise you'll quickly exhaust the buffering capability, in which case the SS GH+ minerals might be what you want.
The SS minerals dissolve pretty quick, but still best to leave the remineralised water for at least an hour, preferably overnight with airstone / pump to circulate and mix, before making final measurements. You might find that GH results go +1 by the next day as the final minerals dissolve.
The above advice from @Zoidburg
about matching the water parameters of teh breeder is very sensible. Neo's have come along way in the last few years and you might find that a local breeder has quite different parameters than recommended ones found online! For example, here in Singapore, shrimp are typically kept at temp's much higher than you guys in the US would recommend / want because our room temp's are so damn hot!