how long to seed a sponge filter ?

[goodgy]

my friend is getting a tank in a couple of weeks and im going to run a big sponge filter in my established tank to give to him so it will hopefully speed up his cycle

whats the correct time period to get the good bacteria built up enough to give to him in the new sponge im adding in my tank ?

 

[Delapool]

I'd add in now. Should take 1 to 2 weeks to get well established which sounds like when the new tank come in.