Two of your posts back you asked a VERY important question. There is a huge difference between CURRENCY & PROFICIENCY. With currency you just need to worry about your landings (if you're taking passengers) and your flight review. Those are just boxes to check off. However, proficiency is what YOU and/or your CFI determine needs to be done in order to keep YOU and your PASSENGERS SAFE (and the airplane usable). This is just an off hand guess, but as a new pilot, you may want to figure at least one flight a month, granted life always throws a curveball.
Concerning when to start flying.... yes, wx will play a significant part in your training. You'll need to get used to all kinds of weather, and most importantly, making the GO/NO-GO decision as PIC. I'd say start now, because those CAVU days can be far and few between.
After your first solo, it's not just building hours, but accomplishing different objectives before your checkride. On the solo flights, you'll be required to complete flight maneuvers, go on cross-country flights, etc. I'm not sure how your FBO will be charging you when you are solo. Most solo flights (depending on where you are, where you're going) require the CFI to sign you off for every solo flight. Some places might charge you CFI time on solo's, others might not. Though the CFI is required to be at base when one of their students is flying solo. When solo, the a/c billing is the same as when you're with a CFI.
Hope this helps.