from now on, since then

(いぜん) Previously, earlier, in the distant past. I.E., in the distant past, people used to poop in a ditch.
(いらい) Since then.
(いご) From then on.
(いこう) Same as 以後, but more commonly used.   $$$
きり xxx (た verb plus)~きり - Ever since I did xxx. Ever since I loaned him the money I haven’t heard from him.
それから Since then.   $$$
(こんご) After this, from now on.