Berliner wessie?

Hello I have some ?'s about brewing this type of beer . First of all I never done a sour beer before so I am johnny come early… My ? is I know it’s a petty easy grain bill to work with the hard part is the souring part an that where I need help …

ok do you do a sour mash or do you pitch some ale yeast with an lacto at the same time an if so how long do you let it ferment an to get sour ?

Here’s basically what I followed.

http://www.wyeastlab.com/hb_lambicbrewing.cfm

Make a 1L starter (DME at 1.020) and add a 5335 package to this. Let it grow for ~3-7 days.
2. Add this to the 5 gallons of Berliner wort. Let this go for 7 days.
3. Add 1007 or 2124 at day 7. A 1 liter starter would be a good idea for the yeast, prior to pitching.
Temp… 68oF for all steps.