Ah, for some reason I thought this was an andriod only game or something. Ok. Grabbed this.
right after clearing the tutorial,you get a free shot at the REM,this is a slot machine that shits new monster to use and of course some of them are really strong and some of them sucks
every two week there is an event where special dungeons and improved XP rate happen and on the weekend of each event,the chance of getting certain kind of strong monsters from the REM triple... coincidentaly we are in the middle of an event right now so if you wait until tomorrow to start you'll have a better chance to pulling something decent
better yet,if you wait until christmas there will be an event where the player themselves cherry picked what monster they wanted and of course they basicaly picked all of the good one
when you do decide to start,follow this guide and try to get something that is at least 3 star or better (on the guide,not on the monster) if you don't get anything worthwhile delete your data and re-do the tutorial again to get another free shot... it's a pain in the ass but starting with the right monster will make a huge difference in the long distance
http://pad.wikia.com/wiki/Valuable_MonstersEDIT: tomorrow greek god and roman god will have higher chance to pop out,you can probably have a decent but not amazing start with any of the greek god (cajole started with apollo) but i'd really would be better if you waited for christmas
or you could just play it until christmas,then try your luck on christmas with the free pul they give you and restart if you don't get anything good out of it... i did a similiar thing first time i played