I asked this question on the Back Fence but, I recall that many people on this forum study Latin and attend/pray the Latin Mass.
Over the summer I want to “re-teach” myself the course. My goal is to be able to to get to chapter 30 by august or at-least 25 by september. BTW I use Wheelock. I also want to be able to start reading and roughly understanding the Vulgate BIble. Any suggestions?
I think I’m going to be the lone voice of “dissent” on this thread: I do not advocate going out and buying Collins simply because your aim is to read and understand the Vulgate.
Regardless of whether you aim to read classical Latin or the Vulgate, basic Latin grammar is basic Latin grammar: until you reach the late Middle Ages there is very little difference in the principles of grammar you must learn.
(Syntax will be a little different, but I think most students of the language can take the differences in stride. Further evidence of this, the quite solid Henle Latin series aims at having the student read first Caesar, then Cicero, then Virgil, but also gives the student some fairly hefty chunks of the Mass and Vulgate, as the grammar and even vocabulary taught applies to Church Latin as well.)
Consequently, the main difference between Latin texts is the order in which they introduce grammatical concepts and the texts they aim the students toward often determine the vocabulary. If I remember correctly, Collins aims for Augustine and Aquinas, and presupposes quite a bit of grammatical knowledge (even more than Wheelock.) My personal opinion is that Collins requires more work than is really necessary to gain basic grammar and is sometimes a bit of an obstacle to self-directed study, when the student has not worked through basic Latin grammar first. Others, I’m sure, will disagree.
If I were to undertake what you are undertaking (and I have in the past) I would stick with Wheelock. Given that your interest is in ecclesiastical Latin, I would skip the chapter exercises (except the readings: those I would do) and instead complete the Optional Self-Tutorial exercises (drills, really) for each chapter. You will find that the grammar you will learn this way applies to the Order of the Mass and the Vulgate as well; however, you will need a lexicon because Wheelock’s will not give you all the vocabulary you will want.
To supplement, I would get ahold of a copy of the Order of the Mass in Latin (can find for free online) and start by translating the Ordinary (with the exception of the Kyrie, obviously

) after I had reached the chapter on the third conjugation. I would also get a copy of the Vulgate (it too, I think, is online) and a decent lexicon and start with the new Testament…
Good luck!