You don't build Ravenous Hydra for Trundle jungle.

There are basically three builds:

1, competitive: Cinderhulk, Boots, Zeke, Knights Vow, rest situational tanky items

2, solo Q/competitive mix: Cinderhulk, Tiamat, Boots, Zeke, Spirit Visage or Knights Vow

3, solo Q bruiser build: Cinderhulk, Tiamat, Boots, Trinity Force, Spirit Visage

So to make bruiser build viable, you would have to rush Trinity Force, which you get around 20-23 minutes, then upgrade Tiamat to Titanic Hydra around 30 minutes, which is not very viable, since Spirit Visage is better choice. If you would build Titanic Hydra you would get Spirit Visage around 35 minutes. You wanna upgrade your Hydra as last item or as 5th.