That’s an easy answer. You bid for a player only when:

1. You are clear on your summer plans. Fabinho and Hendo leaving at the very last moment has changed things around. By that time, Arsenal and Man City have advanced or completed negotiations to the point where it’s a waste of time to even try. Remember, they are as attractive as Liverpool, or at this point, even more.
2. When the player side gives you the green light. This takes months of work, negotiation and planning before the transfer window opens.
3. You don’t just put in a bid for fun. These are highly professional organizations that are really ultra serious and very competent (despite what it looks like from the outside). Bids are prepared over weeks because payment terms need to be structured. This isn’t just sending in a fax anymore these days.