If there was a tool, do you have a spare esp slot for it? Especially if it requires one for each delayed mod!
Fortunately, a delayer only needs to change the starting script of a mod, and that can be merged into the Bashed Patch, so it doesn't need an active esp (I know, because I made the TotF Delayer).
I'm not sure whether just using StopQuest from the console would have any ill effects - using StartQuest to restore it when you're ready. Of course you'd have to know the internal names of all the quests, and nothing would automatically start them again if you forget.
To me, it is a problem that StartQuest is very far from an immersive way to start a quest...
But may I highjack slightly and open up the question of what's an acceptable way to start a mod's quests? Apparently you don't like to be force-greeted by quest-givers, but is that just at the beginning or would it be OK for a follow-up quest after you've done the first, or after you enter a specific interior cell that's obviously related to the mod, or perform some act (like murder someone for the DB)?
Most quest mods you delay by not doing whatever triggers it to begin, so you don't go into the Fighters' Guild if you don't want to join. Or don't pick that up, or talk to that NPC, whatever. How much do you want those to be obvious, and how much do you prefer to be surprised? E.g. If a book triggers the start of a quest, do you want it labelled something like "Mysterious Tome" that hints of a quest behind it, or "Arandel's diary" that could just be background?
Personally, I would want quest mods to add their quests in an immersive way. I do not want a note in my face when I install it (or start a new game), but I want a relatively easy way to get the mod started.
Windfall is a good example: Enter the IC Market District, and an NPC will soon come and ask you for help. TotF is another good example, that a strong enemy attacks you when you sleep, but stops when you successfully fight back, and tells you a story - or it would be good if the enemy waited with the attack until you were strong enough to survive (which is what my delayer does).
I understand that makers of quest mods want people to easily start their quests, but a popup right in the face after installation is no good. Rather, they should include a readme telling how to easily start the mod for those who want it started right away.
Btw, making it so hard to start the mod that you would never do it unless you read how in the readme is not very good either. Ivellon does this, IMHO. There, you must sneak into some special room in the Bruma castle and steal a special book, in order to start it. My characters would never ever do this by themselves, and it feel weird to do this when playing a good character.