Curious... I have two question on symptoms

So I haven't taken a pregnancy test yet. Can't take one till the 25.. but is it possible to have symptoms before hand? Like feeling nausea, having to go to the restroom all the time, feeling hot outta no where...because I've been having all of those oh and headaches. .and my other question Is do you have to have the symptoms all the time as in everyday? Because I don't have the symptoms everyday.... please help me.