It depends how much effort the Sim team has invested in the player. Check the Word on the Street to see what level of commitment the player has to the school. Check your distance to the recruit and remember that Sim teams recruit all players as if they are 250 miles away. Compare your school prestige to the prestige level of the Sim school. There's no set amount of actions that it takes to knock a Sim off a recruit, but all of these things will help tell you how much effort you'll have to pour in to overcome what the Sim has placed on the player. If you're trying to knock a player 1,400 miles away from you that's "tight" with a Sim team that's got a higher prestige than your school, that's going to cost far, far more than going after a player 50 miles away who has "received some interest" from the Sim that's a C- prestige to your C+.
The Sim won't "fight back" (i.e.-add further resources/effort to sign the player) until MAYBE the second wave of Sim effort, which is late in the signing window (and I'm not sure if the Sim adds to unsigned players or simply randomly selects other players at "need" positions to allocate any remaining resources to). The Sim team WILL start to receive consideration credit starting 24 hours after recruiting begins, which can, in a manner of speaking, seem to be "fighting back."