Word of advice. If planning on straight in in VMC it is prudent to stop the 250 knot idle descent on reaching 3000 ft agl and fly level at idle thrust until 210 knots. Then, depending on the situation, you can select flap 1 and then flap 5 still in level flight until flap five manaoeuvre speed - typically 180 knots block below 53T. Then resume further descent at 180 knots (cross-over speed) By doing it that way, you have more flexibility if caught high or close in and by extending the landing gear you can get yourself out of trouble with plenty of altitude to play with rather than belt down fast to 1500 ft straight in and find yourself too fast and close in for comfort. For the 737-200 at max landing weight use three times the height in DME plus 15 miles for top for descent and use o.70 into 280 knots until 10,000 ft. Then level flight at 10 until bleeding back to 250 knots then idle descent at 250 knots to 3000 ft and so on.