First find front speakers within your 30k budget. You'll get very decent fronts for this budget. Later you can replace the center. P15k is actually a bit too much for a center in the context of a 30k front. You can use the excess for interconnects. However until you upgrade to an AVR, I'm assuming you'll be using your HTIB first with the new speakers, you won't get the full benefit of your new LCR but if it were me "ok lang yun" ... the wait will be worth it.
With a budget of P45k for your LCR, I recommend Polk Audio RTi A3 and RTi A4. There should be excess for interconnects and even maybe an interim pre-loved sub.
A good AVR budget to drive a P45k LCR would be about P25k pre-owned, or about P40k brand new.
Later you can upgrade to a better active subwoofer. I would suggest a 15k-20k budget to match your new LCR and AVR.
Good luck.