If your only changing the front pads and discs , just bleed the fronts , theres really no need to bleed em all , but like i said before , if your fluid is old then whilst your on with the brakes you could bleed all the brakes and renew the fluid .
If you want to be pedantic about it the correct sequence for bleeding the brakes is :
With ABS
1. Left hand front.
2. Right hand front.
3. Left hand rear.
4. Right hand rear .
Without ABS
1. Left hand rear
2. Right hand front
3. Right hand rear
4. Left hand front