If the water pump is seaping coolant then you should already be concerned. It is only going to get worse. It could be days or weeks, nobody can tell that for sure. The timing belt has to be removed to replace water pump. I do not know your mechanical expertise so I can't say if it is a do-it-yourself job for you or not, but it is a lengthy procedure since you must remove timing belt as well. I can post instructions for replacing the water pump if you would like me to.