Well, the loss of inital aleph happened in later Hebrew mostly in proper names like אֶלְעָזָר (cf. Fernandéz Grammar of Rabbinic Hebrew p. 13), but the form תְּמוֹל without an aleph is also attested in akkadian timāli and ethiopian təmāləm, which hints at its antiquity.
That makes sense about later Hebrew, תודה רבה, esp. since aphaeresis of aleph is common in certain circumstances in Christian Palestinian Aramaic, Samaritan Aramaic, and Syriac, all Late Aramaic dialects. Kaufman, Akkadian Influences on Aramaic (1974) p. 60, discusses the prothetic aleph in light of Neo-Assyrian but I've never studied that language and am not sure if newer data have changed the situation. Also helpful is the CAL database under ˀtmly, ˀtml and adv. tmly. I'm still not sure whether there is just a sound problem with this Israeli Hebrew word or genuine loss of initial aleph.