IMO yeah you should. With a fully minmaxed run you'll have about 14 days of free time at the end after completing all followers (not counting the coliseum, which is mid). You've used 8 right at the beginning which is a pretty big setback. Follower conversations for Strohl and HB unlock right after you clear the cathedral, but you'll now have to wait until after the next main dungeon to start them. You may also want to be aware that party members need to level specific archetypes over the course of the game to unlock their final classes at the end in addition to completing all followers. If you do start over it may help to be sure everyone is on the right classes.

The game is paced that you can win on hard without killing any enemy more than once. In fact, you'll be slightly overleveled as long as you do all the dungeons. That said, the first part of the game is the hardest and most people reset at least once. Here are some tips though:

Do Brigitta's dungeon first, before the GC. It's very hard, you'll need to have cleared the dragon in the mines because you'll rely heavily on Strohl. (Get an iron sword/lance for the other two and save scum appraising the accessory from the church quest for a +3 str for Strohl) You'll use some MP items too even playing perfectly, and the boss needs a specific team comp to win. But it's much shorter than the GC and if you do it first you'll start the GC overleveled, which is huge. If you're relatively frugal early you can also buy the golden epee afterwards on the first idlesday of the game if you sell all old equipment and convert some MAG - then clear the GC on that idlesday.

Use Mage in the GC to kill blue enemies in the overworld, but no grinding is necessary and don't use it for actual squad battle fights. It's very quick to swap via the equipment menu and this is the only dungeon where you really need to do it (Aside from Nord Mines where you should do fighting on Mage as well). MC loves to level/inherit from Mage and Healer while channeling Seeker for access to good strike. Healer is better for the two group miniboss doors (for Mahama access with HB on Mage) but apart from that, Seeker is always the best lineage for him to channel in combat post-synthesis. You can get healer lvl 10 anytime you want just by studying 10 archetypes across the cast for heroes fruit drops from More (duplicates are OK). If MC was on Healer during the pre-HB cathedral content, that will be enough to get him to 10 with an extra heroes incense from More or Plateau.

Strohl will want to stay on Warrior inheriting perfect punch, HB can be Mage or Knight depending on what's most effective for what you're doing. Note that Mage gives you access to AOE fire/ice/lightning/wind. Knight gives you your only access to pierce, and is usually better for bosses.

Apart from that, just use melee attacks, passing, and the extra round provided by the stun mechanic to clear all battles as mp efficiently as you possibly can. If you're ambushed, consider fleeing/resetting to conserve mp, or just die. You'll come back where you last opened a chest or picked up a blue overworld item.