If I sacrifice a Lonely Poro with Deathknell for Baited Hook, do I draw a card from the Deathknell trigger before resolving Baited Hook?

No, you do not draw the card from the Lonely Poro's Deathknell trigger before resolving the rest of Baited Hook.

According to the rules of Deathknell (Rule 734.1.d.2) and the established interaction with Baited Hook, the Deathknell trigger is created as a "pending item" when the unit is killed, but it cannot enter the chain until Baited Hook has completely finished resolving.

Sequence of Resolution:

1. Activation: You activate Baited Hook, targeting your Lonely Poro.
2. Resolution Begins: Baited Hook begins to resolve. It kills the Lonely Poro.
3. Pending Trigger: The Lonely Poro's Deathknell trigger becomes "pending." It waits in a pending state because Baited Hook is still in the middle of its resolution process.
4. Hook Continues: Baited Hook continues its effect: you look at the top 5 cards of your deck, choose a unit, and play it.
5. Finalization: Once Baited Hook finishes resolving, all pending items finalize and enter the chain. The Deathknell trigger enters the chain, and the unit played from your deck enters the board.
6. Resolution: The chain resolves in LIFO (Last In, First Out) order. This means the unit played from your deck (and any "When You Play Me" effects it might have) will resolve before the Lonely Poro's Deathknell trigger.

Summary: You will resolve the unit played from Baited Hook first, and only after that resolves will you resolve the Lonely Poro's Deathknell trigger to draw your card.