My sister sucked her thumb until she was in the 5th grade....the 1st dentist my parents took her to in grade school wanted to put braces on her, but a friend of my sister's dad was also a dentist, and (thankfully!) he told my parents that putting braces on my sister at that point would be a *complete* waste of money. Within the 1st year after she FINALLY stopped sucking her thumb, her teeth straightened out on their own. (My parents tried EVERYTHING to get her to STOP, to NO avail!)
Fast forward.....my older son (now almost 17) only used his pacifier when he was teething, and otherwise never put anything in his mouth except for food. Oh, and both the pacifier and the bottle got THROWN the week he turned 1 year! (I looked at my mom and my grandma and said "I guess we're through with 'em!" >grin<)
My younger son (almost 3 now) was putting *everything* in his mouth just about all the time <groan>....so we HAD to keep paci's and teether's on hand until recently. On rare occasion now, he will "revert" back to chewing on things, so I get out the "teethers".
As the other mom posted, you can see that "every child is different", so since your little one is so young, I see no harm in letting him suck on his fist. He may decide to take the paci's later on when he is teething, and figures out that it *hurts* when he bites on his fingers.
CONGRATULATIONS, and Enjoy Him while he is so little! :)
~J.~