how to control the time when Ues attach eNodeb in lte.

[Alan Chen]

Now, i want to control the time when ues to attach enodeb. Because at pre-configuration there is a code: ltehelp->attach(uedevice , ebdevice) 

So at the time 0,000000s, system have configuring the attach operation. for example , i want to make simulator do this operation at 2.0000000s . how can i do this.