1/3
1 Year of Service
I have actually done something like that. There's a character at the beginning of the story that the MC could have sex with pretty quickly. This character is a bit of a throwaway character but I do have the option of bringing her back later down the line.One thing you could try if you want to insert some spicy scenes in the early game is a dream/fantasy scene, I've seen this used in quite a few games and IMO it works pretty well.
I've just given the MC a part-time job too, there will be a few more throw-away characters here that the player can choose to interact with or not without affecting the main story but gives the option of quick sex scenes.