I've read the 'ML?' post by Jim and it got me thinking about the two batches of Merlot I have in primary. I obtained fresh grapes from a farm in Escondido, the numbers were 24 Brix and total acid 62.5%. I don't have the test kit for Tartaric or pH (I know, no flaming please).
I crushed and split the 11+ gallons of must into two batches after adding 10 Campden tablets. I let it set overnight and and the next morning added 'Pasteur Red' yeast to one batch and a Lalvin yeast (the name escapes me) to the other. Day 5 showed 1.02 SG on the Red and 1.00 on the Lalvin. At this point I innoculated the Red with White labs Malolactic WLP675. Since I could only get my hands on one tube of Malo I didn't innoculate the Lalvin batch. Also, since I'm new to wine making this year I thought it best to see the differences between with the Malo and without it.
Sorry for the novel my questions a

When is the time to add the Malo?

'From Vines to Wines' has a general statement about 'when the primary slows down' or 'at the end of primary fermentation' add the culture.

What effect does this have if you add late vs. sooner in the primary?

White Labs web site does have general instructions but nothing specific. I understand it's up to the taste of the winemaker but since I'm new to this I'm trying to develope a game plan based on desired effect, in this case for me it's an unknown.
I plan on having the skins in the must for 8-10 days before removing them and transferring to the glass secondary.

From the drive down to pick up the grapes, to the kids in the barrels crushing them, to watching the juice turn to wine, it is fun and quite a diversion from the day to day.

Enjoy and Thanks in advance!

DV