When did 像 become the 'proper' form for "to be like"/"to resemble"? A book I have from 1987 uses 象 to mean "to be like"/"to resemble." For instance it defines 粗沙沙 as:


  形容感觉不细腻，象沙一样粗糙


Nowadays this would be considered a wrong 错别字. The book, though, is only thirty years old.

When did 像 become the 'proper' form for "to be like"/"to resemble"?
From 1986/10.

“像”字有这么多含义，但在《现代汉语词典》中只有第一个“画像、雕像”的意思，这是因为《现代汉语词典》是在1964—1968年期间出版的。 1964年，经中国国务院批准，公布了《简化汉字总表》。在这个总表中，“像”是作为“象”的繁体字出现的，但注明“象和像意义可能混淆时，仍用‘像’ 字”。所以在此之后出版的词典仍保留了“像”字，但是只有第一个含义，也就是说，只有在涉及到“人像、画像、塑像”等情况时，才用“像”，其余都用 “象”。
所以后来经专家学者研究讨论，在1986年重新公布《简化汉字总表》时，对个别字作了调整，其中就包括恢复“象、像”的原状，“象”不再作“像”的简化字。

According to the 《简化汉字总表》 published in 1964, 像 is treated as the traditional character of 象, only used for the meaning of appearance;looks;statue;picture. For other cases 象 should be used.
From 1986 it's repealed, 像 was not treated as the traditional character of 象 again, and regained its meaning of &quot;resemble;be like;take after;similar;alike&quot;.
Even it has benn corrected but the confusion still continues. That might be why the book in 1987 still used 象.
像和象的用法有什么区别
像和象的区别