In balanced scoring with appx 10 defensive starters you'll see Watt go in the 1st or early/mid 2nd round (sometimes as early as 1.01), Kuechly/David will go in the 3rd, Mosley in the 4th, a couple more top DEs (Quinn, JPP) and LBs (Wagner+) will go in the 5th/6th, most teams will have drafted their top two DEs and top two LBs by round 13 or so....but it really depends on scoring and starting positions.
Are you starting DTs and CBs or simply DL and DB? Will you be looking to start 4 LBs every week or 3? Are you starting 2 or 3 DEs? How much is the scoring bonus at DL compared to LB, and DB versus LB? Are there a lot of mandatory starting positions or are there several flexes? All of these nuances change the value between the different IDP positions and the value of IDPs compared to offensive players.
Owners build their IDP in different ways. I prefer to go DE/DL early since I find the drop-off to be steeper at DL than LB, and DL production is less opportunity-based than what it is at LB so I find it easier to find LB production off waivers, but other owners prefer to secure those 2-3 three down LBs to be the main engine of their weekly scoring.
Look at scoring but focus on how steep the drop-off is after the top 3, top 12 and top 36 at the position. 200 pts is generally worth more at DL than LB, particularly if you're starting as many DLs as you are LBs.