In my first (only) game, I think I waited to about 1570. The game ended about 1575.

I didn't really turtle, as I think that will be very hard: you will be handicapping yourself a lot if you stay small. I expanded quite rapidly early on (H/N as Oda) to get about 12 provinces. But then as I approached RD, I applied the breaks - I wanted to fully secure the trade nodes and enjoy a little peace n quiet. When I finally pushed it, I had about 140k in the bank and had upgraded almost everything in my provinces. Even though my holdings were horribly dispersed and I only had three so-so armies, it was rather easy. There was one central faction that was "terrifying" but once I had defeated their three full stacks, there was no real threat. I didn't feel I was waiting a lot - I was largely at peace in the period just before RD, so the turns flew by.

I've been thinking about moving to VH campaigns[1], but trying that as Takeda, the first 5 years made the Oda realm divide look like a picnic. Trying to hold on to North Shinano reminded me so much of trying to hold onto to Shinano in the original STW. A veritable Verdun in the east.

[1]I could not abide going above normal difficulty for battles, as it seemed to unbalance the naval battles so much (you lose fair match up boarding actions; your ships rout first etc). It's a shame, as I've read the BAI is not fully switched on (does not flank) on normal, which would be disappointing if true.