After arrival, she won't be able to submit I-485 until PD current, but your I-485 shouldn't get approved before PD current either. So she needs to be ready to file I-485 the first day PD becomes current to avoid receipt after your I-485 approved. This is the easy part.
The hard part is that she needs to be in H4, which means she needs you to be in H1 for the next several years (You may need to extend beyond 6 years), or she needs to find her own F1, H1, etc before filing I-485.