Thanks, and I can still use it without fear of going up to lvl 100?
Your Homunculus won't go beyond lv 99 unless you Job Change into Geneticist.
But it will store up experience so my recommendation is that you stop using it once you become Geneticist, turn it into Homun S as soon as possible, and then allow it to reach lv.100
It's all here: https://irowiki.org/...ce_and_Leveling
"The level limit for a Homunculus owned by an Alchemist or Biochemist is 99. Once its master is promoted to Geneticist, the level limit is increased to 150. However, allowing a Homunculus to level higher than 99 is not recommended, as it will gain less HP/SP and stats compared to a Homunculus S, so it is advised to keep the Homunculus Vaporized until after completing the Homunculus S quest."