How high should ammonia levels get during a tank cycle?

I have a 10 gal tank that initially had 3 fish in it for about a week and 5 days. 2 died after 4 days and i only had 1 fish for about another 4 days during these 4 days i made 15% water changes because i felt ammonia poisoning was the issue. i then bought 2 more fish and finally found a decent in-tank ammonia indicator to at least see if ammonia was increasing, which at the time before placing the 2 fish in read around 0 (the indicator i think may be slightly inaccurate at very low levels, it may show some even if its not there) and stopped doing daily water changes, seeing as it was low/ not present. it has been going up since i added the new 2 fish, which i suppose makes sense. however this is where it gets a little iffy- about 3 days after getting the tank i used some tetra safestart after hearing many good reviews, i gave it a shot. it actually did seem to help. at this point its a little odd- after testing the water earlier today, my ammonia levels are continuing to rise slowly but steadily, right now at .05ppm over the 4 days, but i am also seeing nitrate for the last couple of days at <,= 20 ppm, which would suggest the cycle has been completed. so my question is how high should ammonia levels get with 2 new fish before going down, how long should it increase for, and just for general knowledge at what concentration of ammonia would nitrifying bacteria require to begin to thrive? ps all the fish have been guppies, since the first 2 died all of the others have been very healthy, constantly swimming and schooling and voraciously eating