In general those things arent made for precise timing circuits, but it doesnt sound too bad. I do tend to trust the 555 more though especially if the power supply varies much.
Nice simple latch, dougy. I was under the (mistaken?) impression the OP particularly wanted to use a 555, but I agree with you that accuracy is not an issue here so a Schmitt-based solution is ok. With your circuit a reset pulse could terminate the solenoid pulse prematurely. That could be an advantage, but if it is a problem for the OP then a monostable could be inserted between the latch and FET, as below:
well the circuit has to be on a printed circuit board :S i will make it on multisim then get it printed but i find it way too complicated! I will need 4 such circuits on a single circuit board.