Not sure about Romanian Red but a good sized Chesnok Red is in the 2.5" range for me.

I like to harvest when the bottom 3 or so leaves are starting to brown. I will dig up one just to check size and decide from there. For me, big enough= I only need a few or one clove when cooking. This depends on variety. I prefer the hardnecks with large cloves + I love scapes. As a bulb, they might be smaller (about 2") than a softneck, but have 4-5 large cloves. I can grow big 3 inch softnecks, but they have a trillion small cloves which I hate to peel to get enough to cook with. Generally speaking I am happy when my bulbs of any variety are around 2".

I prefer the bigger cloves of Japanese and Music which are getting too big for my press as those bulbs pass 2". I am also pretty happy to have hardneck bulbs reach 2". I do not grow softnecks. I also harvest according to the condition of the stem, and get whatever sizes that produces.