It depends how aware of the gap in power Gohan/Trunks become. If not a lot, they both die needless deaths as does Cell (unless he trains more than 4 months

) and anyone else that tries to challenge them. If Gohan and Trunks are aware on the nigh-infinite gap between them though, Bulma builds the time machine far earlier, Gohan delivers the medicine to his father and then pleads with the Dragon Team to help him find Gero and stop him before it's too late. They use the Dragon Balls to locate his lab and break in, with Gohan taking the less drastic approach by warning Gero of his death to come using information on #17 and #18 he has as well as knowledge of Gero in general. It still takes some negotiation for Gero to fully spill the beans on his secret lab where he keeps the plans though, with Gohan and Bulma eventually deciding the best compromise they can give him is a good position at Capsule Corp. to continue his research under supervision. Whether Gero had started modification on #17 and #18 at that point is debatable though, so there's two ways this goes.
1. Future Gohan only finds Cell at the underground lab, destroys it and is saddened to have nothing to save his future. He and Trunks know there's no point returning to their timeline and decide to stay and help in a timeline they can still change. Despite this, however, Dabura shows up 10 years later and kills everyone with ease.
2. Gohan finds the blueprints and returns to his timeline with Trunks, destroying #17 and #18. Knowing how strong Cell may end up being, they find Gero's underground lab and destroy him, saving their future. Unless Gero creates an invention that fills the main cast with enough suspicion towards him to warrant a Rosat trip though, they stand no chance against Dabura 10 years later.