Kids’ Stages & Checklists: Ages 3 to 6

Every stage from preschooler to early school years brings big changes. From clothes and car seats to milk transitions and potty training, keeping track of it all can feel overwhelming. That’s why I put together this age-by-age checklist—so you can stay organized, reduce stress, and help your child thrive.

All About 3

Changes Needed

• Pull-ups: Size 4T–5T (37+ lbs)

• Nighttime bedwetting underwear: Size small

• Clothes: Store 2T clothes in labeled totes/Ziplocs. Move 3T–4T clothes into dresser. Add 5T if growth is fast.

• Labels: Update dresser labels to match current sizes.

• Car Seat: If recommended by manual, move to a booster seat with back + seat belt.
  
  

Transition to Low-Fat Milk

According to How Much Milk Should a Toddler Drink?, the AAP recommends:

• 12–24 months → 2–3 cups (16–24 oz) of whole milk/day.

• 2–5 years → 2–2.5 cups (16–20 oz) of low-fat or skim milk/day.
  
  

According to When Should Kids Switch to Nonfat Milk? (Nemours KidsHealth), whole milk is best until age 2, then lower-fat options can be safe depending on growth.

According to Should You Give Your Kids Low-Fat or Whole Milk?, the best approach is gradual—move from whole → 2% → 1%/skim over time.

💡 Personal Note:

• My little one started 2% Horizon Organic Reduced-Fat Milk at age 3. I also introduced Horizon DHA Omega-3 versions (vanilla + chocolate) to continue brain & eye support after toddler milk.

• His schedule:

  • Breakfast → 1 cup 2% milk

  • Lunch → toddler milk until finished, then switch to DHA milk

  • Dinner → 1 cup 2% milk

  • Snacks → diluted juice or fruit/veggie blends
    
    

My lil one did experience constipation when first switching (one week without a bowel movement). With the help of Miralax, fiber foods like oatmeal + peanut butter toast, and more water, we resolved it. Later, we found Kroger’s Horizon DHA Omega-3 2% Milk—an easier solution since it covers both needs in one.

Potty Training

• At 3, we worked on transitioning into underwear with positive reinforcement (candy rewards and potty chart stickers).

• Alexa reminders every hour + a potty watch kept us on track.

• Progress:

  • Daytime underwear success ✅

  • Pooping still a work in progress, but rewards help

  • Began practicing short car rides and naps in underwear to build confidence
    
    

By age 6, my first son was fully potty trained—able to wipe, flush, and wash hands independently. Nighttime underwear was discontinued at age 6 to encourage him to wake up and use the bathroom, cutting down on accidents. My second son (now 3) is starting this same journey with a mix of success and challenges.

Preschool Transition

Starting preschool can be tough!

• Summer camp or short programs (like YMCA) help prepare.

• Meet teachers early (home visits, tours, photo books).

• Be patient with morning routines and afternoon meltdowns—it takes time.

• Tip: Small after-school treats or fun outings (park, library) helped my son adjust.
  
  

All About 4

Changes Needed

• Pull-ups: Size 4T–5T (37+ lbs) if needed

• Underwear: 4T–5T sizes

• Nighttime bedwetting underwear: Size small

• Clothes: Store 3T in totes. Move 4T–5T into dresser. Add size Small if growing quickly.

• Labels: Update dresser to reflect new sizes.

• Car Seat: If manual recommends, booster seat with back + seat belt.
  
  

All About 5

Changes Needed

• Underwear: Size 4T–5T or size Small (depending on child’s build)

• Nighttime bedwetting underwear: Size small

• Clothes: Store 4T. Move 5T–Small into dresser. Add Medium if growth is fast.

• Labels: Update dresser labels.

• Car Seat: Switch to booster without back (if manual allows).
  
  

All About 6

Changes Needed

• Underwear: Size Small or Medium

• Nighttime bedwetting underwear: Size large

• Clothes: Store 5T. Move Small–Medium into dresser. Add Large if needed.

• Labels: Update dresser labels.

• Car Seat: Booster seat without back (if manual allows).
  
  

✨ Key Takeaway: Ages 3–6 are full of transitions—new schools, bigger clothes, different car seats, and new levels of independence. By keeping a simple checklist for each stage, you’ll stay organized, support your child’s growth, and reduce the stress of these big changes.