Reorder plan: order 500 units of Product A now and nothing else

That is the supplier minimum, and it costs 4,500, which uses all your cash. A is already below its reorder point. B and C have far more stock than they need.

Assumptions

• Lead time: I used the mean of your last four shipments, 22.75 days, not the 21 days quoted. The standard deviation is 3.5 days, and it is the biggest risk in the plan.
• Service level: 95% for A (z = 1.65).
• Demand: weekly sales from the last 8 weeks, converted to daily. Eight weeks is a short history, and I assumed no seasonality or promotions.
• ABC ranking: I used cost value because you didn't give selling prices.

ABC and dead stock

• C dark blue: 120 units (720 at cost) with no sales in 100 days is dead stock. Clear it with a discount or a bundle, and don't reorder it.
• C overall: 540 units is about 430 weeks of supply, or roughly 8 years. Stop buying C and treat the rest as slow clearance.

Per-SKU plan

Product A (order now)

• Daily demand is 21.25 units, with a daily standard deviation of 5.28.
• Demand over the lead time is 21.25 × 22.75 ≈ 483 units.
• Safety stock is 1.65 × √(22.75 × 5.28² + 21.25² × 3.5²) ≈ 130 units.
• Reorder point is 483 + 130 ≈ 613 units. You have 420, so you are below it.
• Cover is 420 / 21.25 ≈ 20 days, which is less than the 22.75-day lead time.
• A order placed today is expected to arrive after you run out, by about 3 days, or roughly 60 units of lost sales. Even a perfect order can't prevent that.
• The ideal order covers the lead time plus a 30-day review period. That is 21.25 × 52.75 + 130 − 420 ≈ 830 units (about 7,470).
• Your cash covers only 500 units. That gives about 23 days of cover once it arrives, so you will need to reorder again very soon.

Product B (don't order)

• Daily demand is 3.1 units. Stock is 310 on hand plus 100 arriving, 410 in total, which is about 131 days of cover.
• Its reorder point is about 87 units, so you won't be near it for months.
• The 200-unit minimum order would only add to the overstock.

Product C (don't order)

• See the dead-stock notes above.

Cash

• The 4,500 goes entirely to A.
• To fund the 330-unit gap (about 2,970), free cash from slow stock. Stock tied up is B at 4,650 (310 units at 15) and C at 3,240 (540 at 6).
• Clearing the dark blue C (720) and part of C's remaining stock is the easiest cash to free. Hold off on B's 100 incoming units only if the supplier allows it.

Risks

• Lead-time variability: at the 27-day worst case, demand over the lead time is about 574 units, so you'd stock out about 7 days before arrival. Ask the supplier about splitting the order, or air-freighting a small top-up (about 60–100 units) to bridge the gap.
• Short history: 8 weeks is a weak basis, and an upswing or a promotion would raise the numbers.
• Supplier terms: confirm the minimum order, payment terms and any freight costs. Freight isn't in the 4,500.

What to measure next

• Actual lead time for each shipment.
• Stockout days for A.
• Weekly forecast error.
• Sell-through of the C clearance.
• Reorder A again as soon as cash allows. Don't wait for the 500 units to arrive.

If you give me selling prices and a freight cost, I can redo the ABC ranking on margin and check whether the 4,500 still buys 500 units.