When can I introduce rice?

Rice, especially in cereal form, is typically introduced anywhere between 4 to 6 months old. Rice (and Oatmeal) cereals are the least of the allergenic grains and this is why most babies are started out with those cereals. Choose Brown Rice or enriched long grain white rice. Rice may be ground up into a fine powder and cooked as you would cook Oatmeal.
Can I Use Previously Frozen Breast Milk or Formula to Make and Thin Cerealsm Vegetable or Fruit Purees?
You should not use Previously Frozen Breast Milk to thin purées that you will then be freezing into baby food cubes. Breast Milk should never be re-frozen in any way or form! Using formula to thin and then freeze Purées is acceptable. Formula companies warn that you do not freeze Infant Formula due to a separation of the formula and not due to any health or nutritional risks. Keep in mind that the amount of formula used in purées is not equal to feeding an infant a bottle of formula.
"Freezing of any Enfamil formula is NOT recommended. Freezing infant formula can lead to physical property changes like fat separation, which may prove difficult for sensitive infants to digest. Freezing will not extend the expiration date of the formula." "Freezing of our products may cause loss of desirable appearance and functionality (though not nutrition), and is not recommended." Clinical Frequently Asked Questions, Storing Enfamil
You may wish to mash or puree your baby foods and freeze without thinning with any liquid. Should you decide to do this, you simply thaw the "un-thinned" food cubes and then thin the food cubes to the desired texture that your infant requires.