Percentages for New Hires...
Engineer, 5 years experience. Product close to launch, series A finished, in a specialized field. What option percentage should this engineer expect?
A company such as you describe ("Product close to launch, series A finished, in a specialized field") might have 20 engineers building the project; or it might have 3 people and several million dollars of hardware. Obviously in the later case a new employee would make a greater impact on the company and thus be able to demand more options.
An engineer such as you describe ("engineer, 5 years experience") might be a 23 year old who got an entry-level programming job straight out of high school and has no particular expertise; or he might have a PhD and be a world-recognized expert in the particular specialized field in which the company is working. Obviously in the later case he would be able to demand more options.
All I can say with confidence based on the information given is that he should probably expect somewhere between 0.01% and 25%.
Obviously, that person wouldn't fall in the middle of your options range (12% is really high).
http://www.venturehacks.com/articles/option-pool-shuffle#mar...
with the top range being for proven elite contributors.
going into the deal everyone has to receive similar stock offers, but after you prove yourself, the standouts can double or more, what the original grant was.